The picture is too dark and there is too much snow on the ground to tell what is really going on. That makes it difficult to even say 'stick a bush in it'. I see furniture which might indicate a patio under there, so for now I'll say, think a decorative fencing panel/screen that can be taller than fence code and make for patio walls of sorts.

Added photo from last summer. Our patio is about 20 feet from fence but this is the view from the patio. The hedge is moe bare now.

It looks like a fence and the neighbor has a hedge. Who has the arborvitae? But yes, you can stick a bush in it. You will have to move the pots, the rhubarb, the green hosta and give up some lawn to do it. Now a close city location is needed for appropriate plant suggestions.

Your snow picture says the right selection of Yew might be what you need.

You could also stick something a little bit in front of where the pot is if you only want to block the view from the porch. Again, you'd lose some lawn.

Do you need it blocked in winter or would something deciduous be okay?

The snowy picture appears to have a healthy Hydrangea to the right. Where’s it gone in the summer picture? It looks happy so why not plant a couple more in the gap?