It's when you know you"re licked, but you begin anyway and you see it through no matter what. Atticus views bravery as a moral thing on an intellectual level, not something that can be proved with a weapon.
Scout - When Atticus takes on the Robinson case, people make fun of Atticus, but not to his face. The children at Scout's school tell Scout about their opinions of Atticus. Scout gets into fights at first, but Atticus tells her not to. By not fighting, she has to endure the painful comments, and she knows that from the start. But she goes through with the plan so that she does not let Atticus down. .
Radley's - tire - doesn't tell anyone about the laughing and lets them think she is a coward. She refuses to play the Boo Radley game anymore, and she is brave because she lets the boys make fun of her. She does this because she knows Boo is watching and she doesn't want to hurt his feelings.
Jem - Jem blows off some steam by beheading some of Ms. Dubose's flowers. This is actually quite a courageous being because it was rumored that Ms. Dubose kept a Confederate pistol beneath her shawl. But again, this is bravery by the definition that "One is brave when he plunges into something and doesn't know what to expect". After Jem destroys Ms. Dubose's camellias, he is punished by being forced to read to her for an hour each day for a month. He knew from the start that it would be a terrible and painstaking process, but that didn't stop him from going each day to read to her. Although he complained on a regular basis, he continued reading to her until the day when he was told he could leave. .
On the contrary, after the trial, Jem has a lot of emotions to sort out. He is both sad and angry about the outcome of the trial, but he is afraid to confront anyone about his feelings, and he keeps them bottled up inside of him. He knows that by speaking about it, he will feel better eventually, but he is afraid that along the way to recovery, he will feel pain and because of this fear, he does not speak of the trial with anyone for a long time.