I don't know quite what I am looking at, can you add a picture from further away, please?

Here is another photo. Thank you!

Your photo did not post. Be sure to wait until it is no longer “grayed out” to submit the post. Sometimes people don’t notice that the picture is not done loading yet.

Of course, now I see it!

I don’t know what that line is, but the contractor should cover that seam between the backsplash and the wall with a color-matched caulk. You should not have to paint it.

Thank you Nancy. If the seam between backsplash and wall has already been caulked with a clear caulk, can I re-caulk with a color match caulk?

"can I re-caulk with a color match caulk"

You must remove the clear caulk and replace it with 100% silicone caulk. You cannot caulk over caulk.