What the N* Word really means?

When I heard my mixed grandchildren saying that word, I freaked out, not hurt them, but tried to teach them. They think I am crazy, because they think they are being cool, because rappers use it, and they want to be like them. I have light skin, and I know there were many races that were slaves throughout history from many different groups of people, and sometimes feel like in USA people are slaves to the system of money... and other things.... still, I believe it is important to not use this derogatory word that calls someone less than simply because of how the person looks. We as humans can do better than that. Love to all!