Okay kiddo, so Lenin was a man who lived a long time ago in a country called Russia. He wanted to make sure that all the different groups of people in Russia could live together peacefully and happily.
One way he tried to do this was through something called a national policy. That's just a fancy way of saying he wanted to make sure that all the different countries and cultures inside of Russia were treated fairly and got to keep their own languages and traditions.
He knew that in the past, the government in Russia had tried to force everyone to be the same and speak the same language. But this just made people unhappy and caused a lot of problems. So, Lenin said that everyone should have the right to be proud of where they come from and what makes them unique.
Overall, Lenin's national policy was all about respecting and celebrating the differences between different groups of people. Instead of trying to make everyone the same, he wanted everyone to feel valued and respected for who they are.