what does Reverend skyles prompt Scout to do as Atticus exits the courtroom?

Reverend Sykes prompts Scout to stand up as her father leaves the courtroom. Atticus has tried his best to save Tom Robinson, and he deserves the respect the standing balcony represents (remember, Jem, Scout, and Dill are sitting in the "colored" balcony).

As the trial concludes in Chapter 21, the black members of the courtroom rise as a gesture of respect for Atticus as, although he was not successful in gaining a not guilty verdict, he had proved Tom Robinson's innocence. Reverend Sykes is moved by this show of respect and instructs Scout to do the same-

'Reverend Sykes's voice was as distant as Judge Taylor's: 'Miss Jean Louise, stand up. Your father's passin'.'