When someone or something is really good at something and takes control over everything else, we say they dominate. Imagine a big, strong lion in the jungle. The lion is very powerful and all the other animals listen to it because it is the king of the jungle. The lion dominates because it is stronger and more powerful than the other animals.
Think of a big tree in a forest. This tree is so tall and wide that it takes up all the sunlight, leaving little for the smaller plants below. The big tree dominates the forest because it is bigger and gets most of the sunlight.
When you play a game and you are so good that you win every time, you dominate the game. It’s like being the best at something and being in charge. Everyone looks up to you because you are the leader and you know what to do.
In a classroom, if one person always talks and everyone else listens, that person is dominating the conversation. They are talking more than anyone else and leading the discussion.