It’s a kind of anime available for, usually, teenage boys.
Unlike Shojo (girl) anime, shounen steers towards more action oriented tales with the intention of highlighting naughty scenes and sexual innuendos. It is also typically written for a younger audience than shojo manga/anime would be, with fewer such topics showing up in it. However most plot lines still focus on romantic relationships involving couples. Themes are often less complex than those in shojo manga or stories derived from them but may also cover subject matter not appropriate for younger children either because it is too sophisticated or graphically violent.