Okay kiddo, have you ever played a game where you and your friends take turns being the leader and making decisions about what to do next? That's kind of how a government works - people take turns being in charge and making decisions for everyone else.
Now, imagine if instead of your friends taking turns being the leader, it was always the same person or group of people in charge. They would have a lot of power, right? That's kind of like what mediacracy means - when a small group of people or organizations control all the information that everyone gets to see and hear.
It's like if you only ever watched one TV channel or read one newspaper, and that channel or newspaper only told you certain things and never showed you any other points of view. That would be a mediacracy because the people who control that one channel or newspaper are basically shaping your opinions and ideas based on what they want you to see and hear.
Some people think mediacracies are bad because they can limit free speech and people's ability to think for themselves. Others think they are good because they can provide a sense of order and continuity in a society. What do you think, kiddo?