"Man pages can be limited, and they're often not great if you're
an absolute beginner, especially if the command is a complicated
one. But they are often enough to get you started -- and in some
cases they can quite genuinely provide an entire manual. Check out
man bash for a very comprehensive example.
One point to bear in mind is that there can be multiple
categories of man page. The ones you are most likely to run across
"1 Executable programs or shell commands
5 File formats and conventions eg /etc/passwd
8 System administration commands (usually only for root)"