Noun form of the verb to revise, which has two meanings

1. (Mainly used in education) To re-read earlier work to improve one's knowledge and understanding of a subject. Often implies memorising for an examination.

2. Examine and make corrections or alterations to (written or printed matter).
"the book was published in 1960 and revised in 1968"

The first meaning is used in British English, but not American English, and is used throughout this course.