The green zone is a safe place where you can go when there is danger around. Think of it like a giant playground with a fence around it to keep the bad guys out. When you are in the green zone, you can play and have fun without worrying about anything bad happening.
For example, if you are in a war zone and there are bombs and guns going off, the green zone might be a little area that the military has set up with lots of guards and barriers to protect people. Or, if you are in a city that is being hit by a hurricane, the green zone might be a shelter or a park that is not in the path of the storm.
The important thing to remember is that the green zone is a place where you can find safety and protection. So if you ever feel scared or in danger, try to find the green zone so you can stay safe!