I think you need to show us these plants and the bookshelf during daylight hours.

I don't know what you keep in those closets but it can be pretty useful to have a table near a closet where you can set things down. A square table or cabinet could fit right into that space. Put some simple framed photos or art on the wall, a small mirror if it's a coat closet (and maybe some hooks for hats).

Maybe you don't need anything there at all. I'm a fan of blank space, giving the eye room to rest.

I agree: “less is more”. I would also leave that space blank.

II'd

Less is more, I agree. If you really want something, I'd soften it with hanging plants or macrame or simlar. Or a pet perch.

Not the art, not the mirror. It's a corner. You DON'T need to fill it.

When you post a question with a single view of a single spot? Nobody has any context, nor any idea of the whole of your space.

I already "have shelves"...............and? We don't see those or anything else

Lots of ideas on line. Hard to tell width, but thought these might work well.

Life will give you something to fill it. You don't have to run out and find "something".

I have no idea since all I see is one little space . This question can only be answered when you show the whole space . IMO not ever space needs to have something often empty space is a nice look. Post a pic of the whole wall and even some of the rest of the space , post here in comments DO NOT start another post.

Maybe a closed shoe cabinet. I see your shoes on the tray.

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This picture was on another thread, the corner is to the right middle:

I’d just have art on the one wall if you’d like, nothing decorative on the floor unless you need some sort of storage. Examples below for size and placement only, not the art. I grabbed this Michel Granger print to use, it wouldn’t actually fit there. We don’t know the measurements for specific suggestions.

(The above art is hung too high, my mock-up skills are lacking today!)

I like this frieze from CB2. I don’t know it the size would work, nor your budget:

https://www.cb2.com/brazilian-white-concrete-wall-decor-panel-ii/s316544

Lots of possibilities, but I’d start with art of some sort on the one wall, the main wall, and see if you’d like to leave the other bare or add something simple.

I think a runner might look nice along there, too, if feasible.

Just to add — it doesn’t have to be framed art. A frieze as above, cool-looking hooks, woven art, etc … just whatever you enjoy looking at.

If you need a place to hang things, a narrow twig hall tree:

Or wall-mounted one:

Coat rack with basket:

Some nice art is all you need

Maureen’s second photo with just the wall art looks good to me.