Miss Stephanie tells Jem and Scout about an incident that happened between Atticus and Bob Ewell earlier in the day. On the post office corner, Bob Ewell spat in Atticus's face and told him that he'd get him even if it took the rest of his life.
Bob Ewell is angry with Atticus for revealing the truth about what happened to Mayella in court. Atticus confirmed what the town had long suspected - that Bob Ewell was an abusive father and terrible person. This threat of Ewell's is not empty. Later in the story, his desire for revenge is attempted on the Finches.
