Words that end with -ion are almost always feminine words in French, so ‘la révolution’. (Please correct me if I’m wrong)
About the meaning of ‘Revolution’: just take a better look at the word itself. A revolution is nothing more than a rotating movement.
This is what happens as well when, for example, a government has been overthrown and replaced by another one.
Revolutions don’t even need to be violent, while the contrary is suggested by Riptide.