Ok kid, have you ever heard someone say the same word over and over again? Like, "I went to the store and the store was big, then I walked in the store and the store had a lot of stuff." How does that make you feel? It can be kind of boring, right?
Well, when writers or speakers use the same word over and over again, it can be boring and repetitive too. So instead, they try to use different words that mean the same thing. This is called "elegant variation."
It's like if I said "I hopped, jumped, and skipped down the road" instead of just saying "I walked down the road." Using different words makes the sentence more interesting to read and listen to.
But, of course, we don't want to use too many different words - that can get confusing. It's all about finding a good balance between repetition and variation to make the writing sound clear and smooth.