Scout means two separate points by these words. But before I proceed, the context is important. Here is the quote:
This order, given by me to Cecil Jacobs, was the beginning of a rather thin time for Jem and me. My fists were clenched and I was ready to let fly. Atticus had promised me he would wear me out if he ever heard of me fighting any more; I was far too old and too big for such childish things, and the sooner I learned to hold in, the better off everybody would be. I soon forgot.
Cecil Jacobs made me forget. He had announced in the schoolyard the day before that Scout Finch’s daddy defended niggers. I denied it, but told Jem.
Based on these words, Scout means to say that it was a difficult time for her, because she wanted to beat up Cecil Jacobs for his words. In the past, Scout would have done so, as she did to Walter Cunningham. However, Atticus made her promise that she would reign in her temper. So, she tried her best.
Second, unbeknownst to her, she and Jem would enter into a world of racism and hatred, as they witness the ugliness of Maycomb in the treatment of Tom Robinson. Shortly hereafter, Scout and Jem would see a mob almost hurt or kill Atticus and Tom Robinson, the unjust trial of Tom Robinson, and the death of Tom Robinson in prison.