man 2 read means “get me the man page for read from section 2”.man 1 read gives you a different man page from man 2 read.man grep
man ls
man sendfile
man ptrace
man printf
man fopen
man null # for /dev/null docs
man sudoers # for /etc/sudoers
man proc # files in /proc
# not super useful
man sl
# explains concepts!
man 7 pipe
man 7 symlink
man apt
man chroot