Okay kiddo, let me tell you about Article 9 of the Constitution of Japan!
This Article is about something called "peace." It was added to the Constitution after a big war that happened a long time ago, called World War II. Japan wanted to make sure that it would never happen again.
Now, this Article says that Japan can't have a regular army. Instead, they have something called a "Self-Defense Force," and they can only use it to defend their country if someone else tries to attack them. So, they can't go and attack other countries themselves.
Some people think this is very important because it means Japan is committed to being peaceful and not starting any more wars. But other people think that Japan should have a regular army so that they can be stronger in case something bad happens.
Overall, Article 9 is about making sure Japan stays peaceful and safe.