IVs = Individal Values
EVs = Effort Values
IVs are random from 0 (Worst) to 31 (Best) in each Stat. Breeding makes a Pokemon have better IVs that it would have in the wild.
EVs are the values you can put where you want. You can have 510 EVs in total and 255 per Stat. Vitimins will raise EVs in a Stat by 10 Points.