Niddesa is a book. It is a really old book from a long time ago that tells stories and talks about things that people believed in a long time ago.
This book is special because it helps people who study religion understand more about the teachings of Buddha. Buddha was a very wise man who taught people a lot about how to be kind and compassionate to others.
The book talks about different stories from Buddha's life and also has many explanations of his teachings. Even though the book is old, many people still study it today to learn more about Buddhism and how to be a good person.