Hey, heres a description of IVs taken from the wiki:
Every stat has an IV ranging from 1 to 31 for each stat (HP, ATK, DEF, SPA, SPD, and SPE), and at level 100, their IVs are added to the Pokémon's stats for their total values. For example, a level 100 Tyranitar with no Effort Values and 1 IVs has 311 HP, however if it had 31 IVs, it would have 341 HP.
So how can i train them? And what's EV too