Okay kiddo, so the black book of communism is a really big book that talks about something called communism. Communism is a way of organizing a country where the government owns everything and everyone is supposed to share everything equally. But some people believe that communism is not a good way to run a country and they think it caused a lot of bad things to happen in the past.
The book talks about all the bad things that happened in countries that tried communism. It talks about how people didn't have enough food, how they didn't have enough freedom, and how the government sometimes did mean things to people who didn't agree with them. The book says that communism caused a lot of suffering and even death for many people.
Some people think that the book is really important because it helps us understand the history of communism and why some people don't like it. But other people think that the book is not fair because it only talks about the bad things and doesn't talk about anything good that happened because of communism.
Either way, it's important to read and learn about different ideas and opinions so we can make up our own minds about what we believe.