Does this mean the same as "That's right"?

Native speaker’s answer
Rebecca
Yes, here, "that's it" means "that's right," indicating that it's correct. "That's it" can also be used to indicate that something has ended or that it's enough. Ex: That's it. I'm leaving. I'm not going to watch any more of this terrible movie. EX: Bring your leg back when you kick the ball. That's it! You've got it! Ex: That's it, Henry. You're doing great.