A complement is the noun in the sentence that is receiving the action of the verb. In English grammar, the complements of action verbs are:

DO (always in the accusative case), and
IO (always in the accusative case),

The complements of linking verbs are:

PN (always in the nominative case), and
PA cf. predicate position

Learn how to diagram complements here.
In Hebrew, the object is often marked out by the object marker word or it is a suffix on the verb itself.