Scout understands why Heck doesn’t want to reveal Boo’s participation in the events of the evening. How does she explain her understanding?

Heck Tate says that it would be a sin to drag shy Boo Radley out into the limelight, and declares officially that Mr. Ewell fell on his own knife. Atticus, deeply moved by this revelation, asks Scout if she understands. Scout assures him that she does, explaining that having it another way would be like shooting a mockingbird. Atticus looks at Scout with a sense of wonder, and thanks Boo for the lives of his children.