A verb is the centerpiece of every clause. There are linking verbs, action verbs, and helping verbs. Unlike a verbal, a verb always has a subject and can be transitive. Verbs are further classified in terms of voice, person, and tense.
In English, there are three simple tenses and these are subdivided further.
(there is no future emphatic tense)
Study chapter 15 in BBG. There are five tenses:
See the verb endings here.
There are two verb forms and seven stems:
The endings for the strong verb are here.