Alright kiddo, do you know what a sign is? It's a little thing that tells you what you should do or what something means.
Now, sometimes people make signs that are not as clear as they could be. They might put up a sign that says "be careful" but not say why or where to be careful. But if you add a little extra information, suddenly the sign becomes more helpful!
This is kind of what an initialized sign is like. It's a special type of sign where you add some extra information to help people understand it better.
Here's an example: let's say you're at a park and you see a sign that says "W dog park". You might be confused - what does that mean? But if you see a little picture of a dog next to the "W", suddenly it makes more sense - the sign is telling you that this is a park where you can bring your dog!
So basically, an initialized sign is just a sign that has extra information added to it in the form of initials, symbols or pictures to make it clearer and easier to understand. It's kind of like a secret code to help people understand a sign better!