Okay kiddo, so a long time ago in a place called Volhynia, some people didn't like other people because they had different beliefs and spoke a different language. This made them very angry and they decided to hurt the other people.
This hurting of people is called a massacre, which means a lot of people were hurt or killed.
When people talk or write about what happened during this time, they call it the historiography of the massacre of Poles in Volhynia. Basically, it means that people are trying to study and understand what happened during this time.
Some people say that the massacre was because of differences in language and beliefs, while others say that the situation was more complicated than that.
The important thing to know is that this was a really sad and scary time for the people in Volhynia. We study it so that we can try to understand why it happened and learn from it so that it doesn't happen again in the future.