Okay kiddo, do you know what "international" means? It means when countries work together and do things to help each other.
Japan is a country, and it has a special policy where it tries to work with other countries on economics. "Economics" is a big word that means how countries make money and trade with each other.
So, Japan's policy is to work with other countries to try to make sure they can all make money and trade with each other fairly. They might make agreements on things like how much they have to pay to buy things from each other, or how they will help each other if there are problems with money or trade.
This is all really important because when countries work together, they can all grow and do better. It's like when you work with your friends on a project, it's easier and more fun than doing it all by yourself!
That's basically what Japan's policy on international economic cooperation is all about. It's like they want to be friends with other countries and help each other out with money and trade.