What does the flag stand for?

During the civil rights movement, heroic men and women seeking justice were often imprisoned.
In our times, athletes who take a knee are heroes.
It takes guts not to follow the politically correct who seem to think that protesting government agents' killing of unarmed American citizens, mostly black, is somehow disrespectful of the flag.
What do they think the flag stands for, anyway, if not life, liberty, and equal justice before the law?
Keith Walters
Monroe