Do you know what a declaration is? It's like telling your mom or dad that you want something or don't want to do something. A declaration is a way of saying what you believe in, and what you want to happen.
In Ukraine, a long time ago, there were some people who didn't want to be ruled by another country, called the Soviet Union. They wanted to be their own country, with their own government and laws. So, they made a declaration, just like if you told your parents that you want a cookie.
This declaration was called the Declaration of Independence of Ukraine. It was written on August 24, 1991, which is also called Ukraine's Independence Day. This declaration said that Ukraine was its own country, and not part of the Soviet Union anymore.
Lots of people in Ukraine were very happy about this declaration, just like if you got the toy that you wanted. They could finally make their own rules and have their own leader. And now, every year on August 24, Ukraine celebrates its independence and freedom!