Okay kiddo, so you know how sometimes things can be really different from each other? Like a big dog and a small cat, or a fast car and a slow turtle. We call those things contrasting, because they contrast or show how different they are.
In linguistics, contrast is when two words or sounds are different from each other and are used to show a difference in meaning. For example, the words "cat" and "bat" contrast in their first sound - "c" and "b" - and that sound difference helps us know which animal someone is talking about.
Another example is the words "big" and "small". They contrast with each other because they show two different sizes of something. Without that contrast, we might not be able to tell if something is really big or really small.
So contrast is when two things are different from each other and are used to help us understand meaning. It's like when you see two toys that are very different from each other and you can tell them apart because of their differences.