After the trial is over, the black people remain in the segregated section of the courtroom and stand when Atticus leaves the building. Scout is told: "Jean Louise, stand up. Your father's passing." What is it that Scout failed to grasp in this scene?

I think that Scout failed to grasp the enormity of what her father has accomplished. Even in defeat, he lost the trial, Atticus had proved without doubt that Tom was innocent. He had stood up for truth in the face of bigoted ignorance and conducted himself with gentle patience.