This phrase is in reference to how Atticus dealt with Mayella on the stand during Tom Robinson's trial. Mayella testified that Tom Robinson raped her and beat her up. During his questioning, Atticus found holes in Mayella's story. He got her confused and made her sound as though she wasn't sure about the details or that she wasn't as strong of a person as she'd like to be. This made it difficult for Mayella to twist the truth to make Tom Robinson seem guilty so she stopped talking. She gave some testimony and then quit answering questions all together. Unfortunately, even though Atticus's questioning of Mayella revealed some significant inconsistencies and improbabilities the jury still convicted Tom Robinson because of his race.
