what does “You just hold your head high and keep those fists down. No matter what anybody says to you, don't you let 'em get your goat. Try fightin' with your head for a change." mean?

I believe this quote comes in Chapter 9. Scout is a fighter. Cicil Jacobs had insulted her father and Scout inflicts the only justice she knows how to. Scout is admonished for beating Cecil up but Atticus uses his own gentle way of convincing Scout that violence should never be the first course of action. Here Atticus instills in scout the trait of self discipline and letting her head deal with conflict rather than her fists.