but I have no idea how to fix the separation!

What separation?

Take a picture from further back of the entire area. Hard to make suggestions without context

Will people be walking here or is this area a planting bed?

Level the area and lay down recycled rubber pavers. They have some give and will make a good walkway path or a pad to expand the outdoor seating area.

You might need to add another step down.

Hey! Ok I will add more pictures. I’m not sure how it originally was, this is how it was when we bought the house. I guess separation maybe the wrong word, but I was referring to where the concrete is coming up and where the concrete is showing under the brick. I’m sorry maybe my new pictures will be better.
The yard is at a slope and it’s so difficult to get anything to stay in place. Maybe this is a Stupid question but how should I level it out? Thank you so much for the feedback and help

I wonder if you want to provide support for the slab. iI.e., concrete jacking. Or, do you want help leveling your yard?