Okay, kiddo, so a long time ago, when people with different skin colors came to America, some of them were treated differently than others. The ones who were treated differently were not paid the same amount of money as the other people who came here.
This problem of not being paid the same amount of money for doing the same work is what we call the "racial wage gap." It means that even if you and a friend have the same job, the same experience, and the same education, you might not get paid the same amount of money just because you have a different skin color.
It's not fair, is it? Imagine if you and your friend did the same puzzle, and even though you both finished it at the same time, your friend got more candy than you. That wouldn't be fair, and the same goes for wages.
Nowadays, people are trying to make sure that everyone gets paid the same amount of money for doing the same job, no matter what their skin color is. It's called "equal pay for equal work." So remember, it doesn't matter what you look like or where you come from, you should always get paid the same as someone who does the same job as you.