I always tel my son, “It’s okay to be mad. It’s NOT okay to be mean.” Repeating it on a daily basis when he’s mad has really seemed to help him sort through things.

Yes he's very verbal hell tell you whats wrong after he's done banging his head like when he bang it its like very hard where he gives himself knots

My son was like that at that age. Is your son very verbal yet? Part of the issue with my son was he wasn't talking as much as he wanted and was getting frustrated. We ended up getting him into speech therapy and behavioral therapy (to help with the anger). His behavioral therapist was able to teach him was to express himself, as well as ways to calm himself down. It worked wonders on him! He used to hit his head on the floor and walls REALLY hard when upset and within a few months of working the behavioral therapist he completely stopped.