Hi there! Have you ever heard of a book that was written by someone, but then another person takes the credit for it? That's kind of what a ghost writer is. It's like a secret person who helps someone else write a book or a story, but doesn't get their name on the cover.
It's like when you and your friend make a really cool sandcastle together, but your friend's mom takes a picture of it and says that your friend built it all by herself. You know that you helped and you're happy that you did, but it's not fair that someone else gets all the credit.
Sometimes, people hire ghost writers to help them write things like speeches, articles or books. It's a secret because the person who hires the ghost writer wants people to think that they did all the work themselves, even if they didn't. It's kind of like a secret helper that nobody knows about.
So, it's like your friend's mom taking credit for your sandcastle or somebody else taking credit for writing a book, even if they didn't do it all by themselves. Does that make sense?