What follows a linking or action verb?
Subject complement or direct object
After a linking verb there is a subject complement.
He is smart. "Is" is the linking verb, "smart" is the subject complement. Subject complements can be nouns, pronouns, or adjectives. Nouns and pronouns that are subject complements are predicate nominatives. Adjectives are predicate adjectives. Smart would be a predicate adjective because it is describing the subject.
After a transitive action verb (action verb followed by direct object) there is a direct object and sometimes also an indirect object. Direct objects are nouns or pronouns.
She throws the ball. Throws would be the action verb, and ball would be the direct object (think: what/whom did she (action verb)?).
Danny throws him the ball. Throws is still the action verb, but now there is an indirect object. The ball is still the direct object; him is the indirect object (remember: what/whom did she (action verb)?). Danny did not throw him, he threw the ball. Therefore, the ball is the direct object. The indirect object tells us to whom/what the action is being done for.
Sometimes, action verbs are intransitive (not followed by direct object).
He nods. Nods would be the action verb, but there is no direct object.
He eats in the school. In the school is a prepositional phrase, and the direct/indirect object can never be part of a prepositional phrase.