It's the part of a sentence that describes the person, place, or thing that's completing an action, or being spoken about. The second section of a sentence contains a predicate adjective (if the speaker or author includes one) and a verb to describe what action the subject is doing.

What is the purpose of predicate nouns or adjectives?

The predicate explains the action. There's often a linking verb (like is or became) in between the two. A predicate nominative is a noun that completes the linking verb in a sentence. Predicate adjectives complete the linking verb by describing the subject of a sentence.

What is the predicative adjective?

an adjective is predicative when it follows a linking verb such as 'be' or 'seem'. In the sentence 'She was right and I was wrong', the adjectives 'right' and 'wrong' are predicative. Some adjectives, such as 'afraid', 'asleep', 'alive', and 'unable' are always predicative.