Okay kiddo, mock language is a way of talking that is not real, but is made up or pretend. It's like when you play make-believe with your friends and make up a language or code to speak in.
Sometimes, people use mock language to joke around or tease each other in a playful way. They might mimic the way someone talks or use silly words and phrases that sound like a made-up language.
Mock language can also be used by actors in movies or TV shows to give the impression that they are speaking a different language, even if they are really just speaking gibberish.
But don't worry, it's all just for fun and no one is actually speaking in a language that you don't understand. Just like when you play pretend, it's all just make-believe!