Hi! Well, unfortunately, I don �t think it �s that easy. Generally, you must ask yourself this question:Does this verb relate some sort of process or a state?
If it relates a process, then the verb is an action verb. If it relates a state, the verb is a stative verb.
Another way:
Can it be used in progressive/continuous tenses? If yes, then the verb is an action verb. Stative verbs cannot be used in these tenses.
Many verbs can be used as action and stative verbs, as always, depending on the context. I believe understand fits in this category.
Understand is typically listed as stative when showing thoughts or opinions:
I understand why you feel that way. Not: I am understanding why you feel that way.
BUT
I am finally understanding stative verbs. He may not be understanding the concept just yet.
Understand can describe a process too, and in this case it would be considered an action verb.
Of course, don �t forget that understand can also be used as a gerund, or an adjective:
She is an understanding person. Adjective
Understanding grammar is an important part of learning a language. Gerund (used as a subject of the sentence)
GOOD LUCK:-) Hope this helps!