Okay kiddo, let me explain what uttering means. Have you ever heard someone say a word or a phrase out loud? That's what uttering is! It just means to say something out loud so that other people can hear it.
Sometimes, people use the word "uttering" to mean something more specific. It can also mean pretending to use a fake check or a fake bank note to buy something from a store or a person. That's not a good thing to do, and it's against the law!
So basically, uttering means saying something out loud or pretending to use a fake check or money to buy something. Thanks for asking, and let me know if you have any more questions!