Okay kiddo, let me explain to you what multiple description coding is! Imagine you have a really cool toy, but you don't want to lose it if you accidentally drop it or if someone else takes it. So what you do is you make two copies of the toy that look exactly the same and play with both of them at the same time. This way, even if you lose one of the toys, you still have another one to play with and enjoy!
Well, this is kind of like what multiple description coding is. When people send a video or audio file over the internet, the file can sometimes get broken or lost on the way. It's like losing a piece of the toy. So, instead of sending just one copy of the file, they can make two or more copies that are slightly different from each other but still show the same thing (or sound the same). This way if one copy gets lost or broken, you still have other copies that you can use!
Think of it like sending two pictures of the same thing but from slightly different angles. If you lost or broke one picture, you could still see the same thing from the other picture, right? This is kind of like what multiple description coding does for audio and video files!