You could have made the back section of the fence solid.

What is your climate zone? Is there a house to go with the pool? Do you have a front garden planted out, or is it also a blank slate? More information/context would help in giving advice.

While you can live with it as is, it would be nice if the walk were wider. As it is, it looks strictly like a utility walk. If it had a decorative quality and were a little wider, it could look more luxurious and two people could walk side by side rather than in single file. Consider at some point in the future extending its width by running a row of brick, laid sailor course, down each side. That would give you 16" additional width.

For hiding the pool equipment, consider a low, curved, decorative masonry wall just large enough to enclose it. It would be the best sound stopper. If you can't do masonry, then some other sort of solid panel would be second choice. If the enclosing feature is decorative, then you do not need to plant solid to hide it. Plants alone would have very little ability to temper sound made by the pump running.

You'll want to do groundcover on the slope as it is too steep to mow comfortably. Liriope spicata comes to mind if that grows there. (You did not say where you were located.) Set back next to the edge of tree line, yard perimeter fashion, you could plant some flowering shrubs that border as much of the yard as you like. Near the pool, surrounding it could be turf. You could incorporate garden beds at strategic places around the pool perimeter, but don't obstruct the view of the pool from the house.

Keep in mind that you'll be figuring out all the small details and creating a plan of this area before you begin actual work. The work would be based on your plan. If you do not think you are able to create the plan, even with help from the forum, you should consider hiring a professional designer to do it for you. If you make mistakes with plant materials or misplacement, it will end up costing you more and you will probably have to suffer living with a result you don't care for.