h5 is a threath and not a pawn break. In this position c5 or f6 are pawn breaks (attacks on the White pawn chain).
To be better at chess you need to study. Often you need explanations and not just best move. Find a book or video that suits your level, interests and learning style and invest some energy (learning is always troublesome).
If you really will like to understand pawn breaks then I would recommend Nimzowitsch's My System.
I don't understand pawn breaks, when to attack, when to defend. The best move here is black plays pawn to h5 but I have no idea why that is a good move. What can I study or practice to understand this situation better? Most of my games I just make a bad pawn move and the engine tells me it is a 3 point swing.