A linking verb (also known as a “copulative”) is almost always some form of the verb “to be” (cf. action verb). It links the subject with the complement and the resulting clause is called an “equative clause”. The complement of a linking verb will always be either a predicate nominative or a predicate adjective.
In Greek, the linking verbs are ειμι and γινομαι.
In hebrew, the linking verb is היה.