In the background is a row of Arborvitae evergreen trees. Being evergreen, the Arborvitae makes a good choice for creating privacy screen hedges and plantings around pools. The leaves on these evergreens are different than other leaves and pine needles are generally easy to maintain and clean up. Still, it's a good idea to keep these and all plants a good distance from the edge of the pool to keep debris in the pool to a minimum.
As for the rest of the landscaping around this pool, you can see the pavers used are in bad shape. While pavers like these are good for absorbing water and preventing puddling, there are much better choices for decking around pools. Cool decking or decorative concrete are much cooler, more beautiful, and many times more economical.