The “man” is a short term for manual page. In unix like operating systems such as linux, man is an interface to view the system’s reference manual.
A user can request to display a man page by simply typing man followed by a space and then argument. Here its argument can be a command, utility or function. A manual page associated with each of these arguments is displayed.
If you will provide a section number in the command, then man will be directed to look into that section number of the manual and that section page will be displayed. And if not, then by default it will display the first page and you have to go through the entire sections in a pre-defined manner.