Film-out is when a movie is made into a physical film that can be played in a movie theater. Just like how you need to print out a picture to hang it on your wall, when a movie is made, it needs to be turned into a physical thing that can be shown on a big screen.
To do this, the movie is put onto a special kind of film tape that can be projected onto a huge screen. Think of the film tape as like a super long strip of paper with tiny little pictures on it that move really fast when the film is played.
Making a film-out involves taking all of the digital images and transferring them onto the film tape, kind of like making a copy of a drawing onto a piece of paper. This can be a complicated process that involves some special equipment and people who know how to use it.
Once the movie has been transferred onto the film tape, it can be played in a movie theater for lots of people to see. That's how movies have been playing in theaters for a very long time, even before we had all the fancy digital technology we have now!