The 30-degree rule is a fancy way that grown-ups use to say “Change the camera angle by at least 30 degrees between shots.” This means that when shooting a video or movie, the camera should not stay in the exact same place for two shots in a row. This is important because it helps the viewer feel like they are watching something new and different, instead of just seeing the same thing over and over.
Think of it like playing with your toys. If you always have the same toy in the same place, it would get boring after a while. But if you move it around and play with other toys too, it makes it much more fun and interesting. The 30-degree rule helps movies and videos to be more fun and interesting by making sure the camera moves around and shows different views.