Voice-over, simply put, is when somebody talks over a video or movie, explaining or giving more information about what you see on the screen.
Imagine you are watching a cartoon movie. The characters are moving around and talking, but you may not understand everything they say. That's where a voice-over comes in. A person with a nice voice talks over the movie, filling in the blanks for you. This person might tell you what’s happening in the movie or explain more about the characters and their emotions.
Sometimes, voice-over is also used in TV commercials. You might have seen ads where a person talks about the product being sold while you see the product being used on the screen. That's voice-over too.
Overall, voice-over is an important tool to help you understand what's happening in a video or movie. It’s like having someone next to you explaining everything that's going on, so you don't miss anything.