For example,
[root@fedora ~]# whatis pwd
pwd (1p) - return working directory name
pwd (1) - print name of current/working directory
pwd [builtins] (1) - bash built-in commands, see bash(1)
pwd.h [pwd] (0p) - password structure
What are those 0p,1,1p? Sometimes, I also see the word rpm in the brackets.