The mammotrectus super bibliam is a really old book that talks about the Bible. It was written a long, long time ago by a man named Johannes Herolt. He wrote it in Latin, which is a language that was spoken a long time ago by people in Europe.
In the book, Herolt explains different parts of the Bible and what they mean. He wrote it to help people learn more about the Bible and understand it better.
"Mammotrectus" is a fancy word that means "milking stool," and "super bibliam" means "about the Bible." So the title of the book is kind of like saying "a milking stool for understanding the Bible." A milking stool was something that people used a long time ago when they were milking cows or goats. They would sit on the stool while they milked the animal, so the animal wouldn't be uncomfortable.
So, just like a milking stool helps make cows comfortable while they're being milked, the book helps people understand the Bible better by explaining things in a way that's easy to understand.