The child tries to describe any object, event, concept, not calling it. And you have to guess what was going on. For example, a child explains: it is edible, can be sweet or sour, grows on a tree, can be green, yellow or red, round or nearly round. What is it? As you guess. Then swap roles. Better to start with simple, familiar objects. Then you can go and abstract concepts. For example, explain to the kid what "offense" or "joy". You can play with the whole family.