A noob is a person who is new to something and doesn't know much about it. It's like when you first start playing a new game or trying a new activity and you don't know all the rules or how things work yet.
Think of it this way: Imagine you are going to start playing soccer. You've never played before, and you don't know much about the game. You would be a "noob" at soccer. You might need someone to show you how to kick the ball, explain the rules, and help you learn some basic skills.
Being a noob is not a bad thing. Everyone starts out as a noob when they try something new. With time, practice, and experience, you'll become less of a noob and more of an expert. Just keep trying, asking questions, and learning, and you'll get there!