Leveled Reader is one of the templates you can use to make a new book or shell book.
A reader is a book that is used for reading exercises.
A leveled book collection is a set of books that is organized in levels of difficulty.
A leveled reader is one of the books in that set.
Each level has a limit for word length and sentence length. Word length, sentence length, and other factors are changed in a sequence of levels.
Lower levels have shorter books that are easier to read. They have shorter words and sentences. Higher levels have longer books that are harder to read. They have longer words and sentences. This allows people who are learning to read find a book that they can use for practice. Each person can progress through the levels to improve their reading skills.
When you make a book from the Leveled Reader template, it is generally similar to making a book with the Basic Book template. But then you need to set up the levels. See Leveled Reader Tool overview.
Leveled readers and decodable readers are different.
https://vimeo.com/123325405 is a video that can help you learn about the Leveled Reader Tool.
https://vimeo.com/channels/bloomlibrary/videos/search:Reader/sort:alphabetical/format:detail
https://pdf.usaid.gov/pdf_docs/PA00JW1V.pdf
https://www.scholastic.com/teachers/article/what-leveled-reading