If you want to know more about a given command options and usage, you can consult the commands manual, or “man page”. The syntax for the man command is:

man [section] <man_page>

Sections are like different chapters of a big book, each one specific to an aspect of the system. Some commands might appear in different sections, so you might need to specify which section you are interested in.

Sections are numbered from 1 to 9, and there's a 10^th one, called n. You can also specify a to display all matching sections for a given man page. If you omit the section parameter, the first matching man page is displayed.

man has its own man page, execute man man to display it.