"Feminine" behavior would be the behavior that the culture one lives in
standardized as "feminine". For example, playing with Barbie or watching romantic movies is what American culture would consider to be a "feminine trait", thus you have feminine trait if you live in America.
Of course, being feminine does not merely pertains to one's behavior, it is also including one's looks. For example, a female body builder would not be considered feminine in America (or
anywhere in the world for that matter; try the
Andromeda galaxy, ladies). Another example would be a male that sways his hips when he walks; that would be considered feminine in America (and most of the world also).
Once again, "femininity" is not merely limited to looks and behavior. Various other factors include clothing, personal belongings, sexual orientation, etc.