The 3 main types of play are: social, predatory and sexual play. Social play helps cats learn limits and boundaries.
Through social play cats learn how intense they can play without hurting their playmates. Kittens communicate to each other through vocalizations and body language when their playmate is playing too rough. Social play also helps develop important fighting skills, necessary for survival. Better to practice with a sibling then learn in the real world where the stakes are higher.
Predatory play is very important for teaching kittens essential hunting skills. This type of play is typified by kittens stalking, lying in wait and pouncing. In the wild, kitten moms often bring small prey animals back to their kittens to help them develop essential hunting skills.