This h4-h5 is quite interesting, especially since it forces black to play h6 to hide the bishop, which gives White the advantage in development. As you can see, White has advanced both his knights to the kingside, and is preparing to bring both his bishops in the game. Black on the other hand, has a weird kingside structure in my opinion.
Not only that, White has a lot more space to work with. White is also protecting that h5 pawn well, as well as possibly playing Be2 and maybe maneuvering the knight to secure that h5 pawn well.
The h5 pawn is also preventing Black from playing g6 to possibly fianchetto his bishop.
And as what @briantowers has mentioned, Black's bishop is now on h7, and after Bd3, White forces the capture.
Furthermore, this results in White forcing black to castle queenside, unless you want your Black king to be in grave danger. However, if Black castles queenside, there it the possibility that White can also start an attack on the queenside. However, as @PhillipRoe mentioned, white sort of has to castle queenside after pushing that h pawn so far, and further attacking the Black king using White's queenside pawns can be a bad idea, due to it opening up the White king.