Let's take a look at our ls -l output and inspect the first column of the listing:

$ ls -l /bin/bash
-rwxr-xr-x    1 root     wheel      430540 Dec 23 18:27 /bin/bash

This first field -rwxr-xr-x contains a symbolic representation of this particular files' permissions. The first character (-) in this field specifies the type of this file, which in this case is a regular file. Other possible first characters:

'd' directory
'l' symbolic link
'c' character special device 
'b' block special device
'p' fifo
's' socket