The Markov Chain Central Limit Theorem is a way to figure out what will happen in the long run when we do something many times. It's like a magic trick where we can figure out what will happen in the future, even if we don't know much about what is happening now.
Imagine you have a bag of candy. You reach in and pull out one candy. Then you reach in again and pull out another candy. You do this over and over again. Each time you pick out one candy, the chances of getting a certain type of candy change. You might get more of some types than others.
The Markov Chain Central Limit Theorem helps us figure out what's going to happen in the long run, even if we don't know how many candies of each type we will get in the beginning. It basically tells us that if we do something a lot of times, the odds of getting a certain type of candy will eventually even out. So, even if we don't know how the candy is distributed in the beginning, eventually the chances of getting each type of candy will be about the same.