Examples of simple predicates are "The child went home" or "The child threw the ball." In both of these instances, the subject of the sentence is "the child," and the predicate is "went home" in the first case and "threw the ball" in the second.
A predicate is that part of a sentence or clause that makes a statement about the subject of the verb. In the examples, "the child" is the subject about whom something is being said. A predicate adjective is one that is used after a linking verb to describe a noun that comes before the verb, as in the example, "The sun is hot." The predicate adjective is "hot."