When two countries, Greece and Turkey, don't always get along, it's like when two kids don't always want to share their toys or play together nicely.
As adult countries, Greece and Turkey have had some disagreements over things like borders, the rights of certain groups of people, and even control of small islands in the sea between them. These disagreements have sometimes led to arguments, or even fights, just like how kids might argue or push each other when they don't agree.
However, adults and countries are supposed to be better at talking and finding ways to work things out peacefully. Greece and Turkey have tried to do this many times, but sometimes they still have trouble agreeing on things. It's important for them to keep trying, though, so they can be better friends and neighbors.