Traditionally, manpages are divided into nine sections, where section 1 consists of user commands, section 2 contains system calls, and so forth. By default, all sections are consulted, so the section option serves to bypass the most common entry and find an entry of the same name in a different section (e.g., man 2 nice).
Numerous other utilities—such as info, xman, and the Konqueror browser—can also display manpages