What is the conversation in chapter nine between scout and Atticus and what does it tell us about these two characters and what does it tell us about racism about the south

It's saying that Atticus is a respectable person who doesn't see race as a reason to or to not defend someone; he's not racist. It shows that racism in the south is common, and that because of that, Scout has grown up being taught to be racist. Atticus is trying to turn her away from that and get her to focus on the person's true self, not the color of their skin.