Okay kiddo, let's imagine you have a group of friends and you all have walkie-talkies to talk to each other from different parts of the playground.
But sometimes, other people with walkie-talkies try to talk on the same channel as you and your friends, and it gets really confusing and hard to understand each other.
That's where ITU radio regulations come in. The ITU stands for International Telecommunication Union and they make rules that all countries and people with radios have to follow.
These rules help make sure that everyone can use their radios without interrupting or interfering with each other. They also make sure that different countries can communicate with each other and that the signals from the radios don't cause any harm to people or things around them.
Just like how your teacher has rules in the classroom to make sure everyone can learn and be safe, ITU radio regulations make sure everyone can use their radios safely and effectively.