A page is one sheet of a book, magazine, or other collection of papers. You can read a page in a children's picture book much faster than a page of War and Peace.
If you read a book, turning its pages, you page through it, and if you write a number on each unnumbered page, you could say you page it. There are other pages too, including a medieval knight's assistant and an errand-runner in a legislative office. You can also page someone, or call for them over a speaker in a public place — this meaning comes from the idea of "sending a page to fetch someone."