Okay kiddo, let me explain this to you in simple words. Have you ever seen a toy that looks really cool, but when you open it, there's nothing inside? That's kind of like what a nomen nudum is. Nomen nudum is a Latin term that means "naked name."
Imagine, you heard someone say a name of a toy that sounds really interesting, but when you try to look for it, there's no picture or description of it. That's because the name they mentioned was just a name without any real meaning or description. Scientists use this term when they give a name to a creature or plant, but then they don't give enough information about it for other people to be able to recognize it.
So, a nomen nudum is like a name without any description, and it's not very helpful to anyone who wants to learn more about it. Scientists want to avoid using nomen nudums because it can lead to confusion and make it hard for other people to understand what they mean.