I am male and my breasts feel like it hard around my nipple and is very sensitive in one of them.

Gynecomastia?: Probably this is nothing serious. Gynecomastia is female type breast development in males. Mild gynecomastia, including firm tenderness under the nipple, is a fairly common symptom of puberty in young men. This might be most likely if your own puberty was on the late side. But if this persists more than a few weeks, best to see a doctor, preferably an endocrinologist.