Okay, imagine you draw a picture or write a story. That's called your "creation". Now, you can decide if you want other people to use your creation or not. If you don't want them to use it, that's okay. But, if you're okay with people using your creation, you can give permission for them to use it. That's what's called a "public copyright license".
It's like you're giving a gift to everyone! You're saying "Hey, everyone can use my creation as long as they follow some rules". These rules can be different depending on what you want. For example, you might say "People can use my creation, but they have to say I made it" or "People can use my creation, but they can't make money from it".
When you give a public copyright license, it means that your creation isn't just for you. Other people can use it too! This is really great because it means that more people can enjoy your creation and be inspired by it. Imagine if you made a really cool drawing, and lots of people got to see it and even make their own versions of it! That's the power of a public copyright license.