So here are the photos:

This is what you see, when you enter the bedroom.

This is what you see, when you look left.

Now I'm standing in front of the night table (to the right of the bed in the first photo). The door you see leads to a small toilet.

This is what you see, when you stand in front of the toilet door. The other door leads to a small closet.

I would be most greatful if you could advise me on how to make this room look cozy. It would be best if you could suggest some general tips along with ikea products (it's easiest for me to shop at ikea).

One of the things I need for sure is the overhead lamp. You can't see it in the pictues but it is above the foot of the bed and currently it is just a lightbulb on a wire...

Nice soothing color on the walls. Pillows 2 or 4 regular pillows and 3 throw pillows. Layers of bedding in soothing tones or whites. A fluffy Throw Blanket tossed on bottom of bed. Night Stand Accessories [2 books and a cute cactus on one side and a vase or something you like on other for example] with Lamps. Also, a Cool Chandelier from Ikea like this one. And a couple of pictures for the walls.

I'd go and wander around and see what you like.

Here are a few ideas:

https://www.ikea.com/us/en/rooms/bedroom/gallery/

I would go for something along this line (West Elm furniture) to add texture, color, and warmth.

https://www.westelm.com/products/modern-bed-set-h1509/?catalogId=71&sku=8807880&cm_ven=PLA&cm_cat=Google&cm_pla=Furniture%20%3E%20Beds&cm_ite=8807880&gclid=EAIaIQobChMIw5GugL2f5gIVgZ6fCh34NQ_SEAQYASABEgLn2_D_BwE

Adding some drapes will add some coziness and style to your bedroom. You can continue with a very light neutral to keep it calm or add a color that you like and use that to coordinate pillows and throws. Some artwoork on the walls, lamps amd a small rug will also add some interest and character to this room. Best wishes!

Here is a pretty bedspread that I think could set the tone for your room. Ikea has some great pieces that would help fill in the details.

French Market Quilt - Trapunto Quilt, Vine Quilt | Soft Surroundings · More Info

https://www.mydomaine.com/chic-ikea-bedrooms

IMO, to achieve a cozy look, you need to bring in some more warmth. Your floors and windows have a nice warm wood tone but the rest of your room is a bit on the cool side. It definitely leans to the clean, Scandinavian look now. How about bringing in wood based lamps for your bedside tables? Adding a fluffy, larger comforter will help as suggested. Floor to ceiling drapes will add warmth and coziness. I would also consider adding texture with a pretty throw and a light accent color to keep with the clean look you have going. https://www.ikea.com/us/en/p/hoensbaer-comforter-cooler-10271675/

https://www.ikea.com/us/en/p/dunmal-throw-white-50465407/

https://www.ikea.com/us/en/p/ofelia-throw-white-30139623/

These are not from IKEA, but I think they would work well

https://www.ikea.com/us/en/p/annalouisa-curtains-1-pair-white-50410815/

Guessing you like white and want to keep the room mostly, if not entirely, white?

If this is a full bed, consider investing in a queen sized spread or comforter -- even if you still choose solid white, you might consider white on white. Even if you need to add a stitch or pinto the two corners at the bottom of the spread or comforter to keep them from dragging on the floor, it will be worth it to have the bed full covered.

Do choose pillow shams to match the spread or comforter. If you choose white, choose two white matching pillow shams but also choose two more shams in the same style but either in your favorite (different) color or with both white and your favorite color.

For your bedside cabinets, see if you can find a pair of tall thin lamps with medium to large white shades. If you choose lamps with a straight smooth post, you could paint it white as well. Alternately, if you could find the same color wood as the window trim. that would be worth considering.

If you could move the headboard of your bed away from the window enough to add a table or or shelf or shelving unit (white would work) the width of your bookcase, you could add a row of white flower pots or interior rectangle planter(s) to add some live plants to your room -- something that stays green/attractive year round but blooms, too.

https://www.farmersalmanac.com/thanksgiving-cactus-christmas-cactus-73148

Bright Scandi bedroom · More Info

Bright Scandi bedroom · More Info

Scandi Dream Home · More Info

Scandi Dream Home · More Info

Here are a couple of nice Scandi looks to inspire...

Beautiful room, I love your windows!

Layer textured blankets on the bed. Fuzzy faux-fur or chunky knits.

Lamps on the nightstands. I like @katinparadise's suggestion to echo the wood tones of your windows.

Plants on the windowsill, nightstands, and/or dresser.

Ceiling lights:

• STORMVIND
• GRIMSÅS
• RAMSELE

Start by getting bedding you love then come back and show us that Right now other than you like minimalism is just not enough info for really concrete ideas. I always start bedroom decor with the bedding it sets the tone for the space and also starts the color palette

The large mirror is cold looking and not cozy. I suggest finding a different home for it - perhaps in a hallway nearby.

What country are you in? Based off your windows and plugs my guess is somewhere in Europe. I know IKEA US has different products than other parts of the world. I'd love to pull some pieces from the IKEA near you so it's actually helpful. Beautiful space.

Thank you for all the comments, I found some great ideas in them! I think I will start with bedding and lamps.

@User I live in Poland, you are right about Ikea having different products across the world.

All your ideas and comments are welcome!

Here are some ideas from the Poland IKEA that I think would make a neutral, yet warm space:

Also, our windows are manufactured in Krakow -such a small world!

You mentioned "overhead" lamp. If you're replacing your overhead light fixture, consider a modern ceiling fan with light IF your box is the kind that can support that weight.

You might want to choose a small one so it doesn't overpower the room -- perhaps white and silver for your colors.

https://www.google.com/search?q=modern+ceiling+fan+with+light&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjtjeujp6LmAhUET98KHQiHBC4Q_AUoAnoECA4QBA&biw=1328&bih=617#imgrc=8V_u1BfXwSTIeM:&spf=1575679431308

Do let us know how your project turns out.

If there is room, you might consider a rectangle shaped storage ottoman at the foot of your bed -- seating to change your shoes and a place to store them ... or a place to store bedding not in use.