is the command, -l
is the option. There's a space between them. ls -l
Edit: To clarify:
A command consists of one or more "words" separated by blank space.
The first word is the command name.
(Two simple commands. Command will run using default parameters)
After that come options, which control the behavior of the command. These are usually preceded by - or --.
Then there are arguments. These are usually the filenames or other strings that the command will operate on.
ls -l /home
Sometimes an option is also followed by an extra argument or added setting.
firefox --new-window http://www.linuxquestions.org
And finally, multiple short options can often be combined, if they don't need to be followed by extra arguments.
(This is the same as "ls -a -l")