If you have never heard of a Beat Sheet this is a concept made popular by Blake Snyder. He was a pitch man in Hollywood working frequently with Disney. He noticed a pattern from doing hundreds of pitches. He always seemed to get questions about the same few plot points. Before going into a pitch he would make notes of those main plot points which he turned into a book called Save The Cat. You will notice that ever film you watch has these same plot points. It goes from big budget to small indie films that win the festival circuit.
Some people love the beat sheet and other hate it. They refer to it as ad lib movie making. Writers feel blocked in to a formula. The reality is that those beats are just how we digest story. If you write a script that missed these beats then you probably need a few rewrites. The only movie I can think of that didn’t follow the beats was Die Hard 6. And it was a failure which probably had the beats originally.
This website will use movie samples to prove how important those beats are.