My child has cat bites. What is the best way to explain it to the other kids?

Complicated. Real question is why did the cat bite her. Cats are generally docile animals and do not hurt people unless scared or provoked. Cat bites can also get infected and could be serious if untreated. If the kids are hurting the cat, that has to stop, if the cat is sick or scared and is attacking, that has to stop. The whole point of having pets is to enjoy the friendly relationship.