Okay, so you know how sometimes people from one country go to another country to live, work, or visit? Well, some people from Russia went to Ukraine because they wanted to live there or because they had family and friends there.
But then, some Ukrainian people didn't want the Russians in Ukraine because they thought the Russians were trying to take over their country. This made a big argument between the two groups of people.
Then, some Russian soldiers came and took control of a part of Ukraine called Crimea. They said they needed to protect the Russian people who lived there from the Ukrainian government. This made the argument even bigger and some people from both sides got hurt or killed.
Now, some people are still arguing about who should be in charge of the land and what rights the Russian people in Ukraine should have. It's a very complicated situation, and some people want it to be peaceful, but it's not easy to make everyone happy.