Okay kiddo, let's talk about the Byzantine text-type. When people wrote things down a long time ago, they didn't have computers or printers like we do today. They had to write everything by hand, over and over again.
But sometimes, when people copied a book, they would make mistakes. Maybe they spelled a word wrong, or added an extra word that wasn't there before. And when someone else copied that mistake, it would keep getting copied over and over again.
So over time, lots of different copies of the same book would start to look slightly different. Some of them would have more mistakes than others.
The Byzantine text-type is a group of books that all have very similar mistakes. These mistakes happened because the people who copied those books were all working in the same place, in the Byzantine Empire.
People who study these books have noticed that the Byzantine text-type is the most common type of text for the New Testament in Greek. It's like a big family of books that are all related to each other because they have the same mistakes.