ELI5: Explain Like I'm 5

Stand-in

Okay kiddo, imagine you're in a school play but you can't make it to one of the rehearsals. So your friend steps in for you and pretends to be you during that part of the play. That's kind of like a stand-in.

In movies and TV shows, sometimes the actors need a break or can't be there for certain scenes. So another person is hired to stand in for them. They wear the same clothes and stand in the same spot so the cameras can film the scene.

The stand-in is like a temporary replacement, but they don't actually act or speak any lines. They just stand there so everything looks the same for the cameras. It's kind of like a double for the actors, but only for certain scenes.