The fist represents the Power of Women. When united and standing together, we can create change and make the world a better place, just as so many before us have done.
"Equality for women isn't a women's issue. When women fulfill their potential, everyone benefits. Equality means better politics, a more vibrant economy, a workforce that draws on the talents of the whole population and a society at ease with itself." (WomensEquality.Uk.Org)
Just for a fun refresher:
Here is a list of famous feminists in history.
Here is a history of the Women's Rights Movement from 1848.
Here is a great book from Adichie, a New York Times bestseller—a personal, eloquently-argued essay, adapted from the much-admired TED talk of the same name.