Okay, so the Kuril Islands is a group of small islands that are located between Russia and Japan. Both Russia and Japan believe that the islands belong to them, and this disagreement has been going on for a very long time, even before you were born.
So imagine you have a toy that you and your friend both really like to play with. One day, you and your friend have a disagreement over who the toy belongs to. You both think it's yours, and you can't come to an agreement. This is kind of what's going on with Russia and Japan and the Kuril Islands.
Before World War II, the Kuril Islands belonged to Japan, but after Japan lost the war, Russia took control of the islands. Japan doesn't think this is fair and wants the islands back, but Russia doesn't want to give them up. This is called a dispute or a disagreement.
To make things a little more complicated, not everyone living on the islands agrees on who they want to belong to either. Some people who live on the islands are Russians, while others are Japanese. Both sides want their island to belong to them.
The dispute has been going on for a long time, and it's not clear when or if it will ever be resolved.