A horror movie is like a story that tries to make you feel scared and surprised.
It's like when you're playing hide and seek and suddenly something jumps out and says 'Boo!'. Except in a horror movie, the scary surprises are on the screen.
For example, imagine you're watching a movie about a big, furry monster that comes out at night to scare people. The monster might make spooky noises or appear suddenly to try and scare the characters in the movie.
Another example is a movie about ghosts haunting a haunted house. The ghosts might make things move by themselves or whisper creepy things to the characters.
So, a horror movie is like a big, make-believe game of scare with lots of twists and turns to keep you on the edge of your seat!