The phrase “dont use big words” means that you should avoid using words that are complicated and difficult to understand. Instead, it is best to use simpler words that are easy to understand. For example, instead of using the word “stipulate”, you could say “say” or “state”. An analogy that can help you understand this phrase is that if you are giving directions, you would not use a lot of street names that most people don’t know. Instead, you would use landmarks that people know and are familiar with. A fun fact about the English language is that there are over a million words, but the average person knows around 15,000 of them.