To keep your son from biting others he should be first reminded, in a language he will understand, that biting is not ok. You should monitor him when he is playing with other children. If you seem him about to bite, take him away and tell him again that it is not ok. If he does bite again take him out of the situation and tell him the rules about biting again. He will eventually and quickly understand that if he bites he gets a time out. Never bite to teach him a lesson though, this really just enforces the bad behavior.