An action verb denotes physical, mental, or even emotional activity. The word run is obviously an action verb. But so is think.
Every action verb is either transitive or intransitive. A transitive verb is one that can attach directly to a noun (the direct object of the verb). An intransitive verb cannot attach directly to a noun; an intransitive verb needs a preposition to form a relationship with a noun.
Thus, the action verb hit is transitive. You can hit a ball.
But the action verb proceed is intransitive. You proceed with the investigation.
Many action verbs have both transitive and intransitive definitions. The verb run is intransitive, as in run across the field. But it is also transitive, as in She runs the organization.
Top writers develop their writing styles around the action verb.
The other verbs in the English language, which are not action verbs, are (1) the verb to be, (2) the linking verb, and (3) the auxiliary verb.