ls 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.
Code:
(Two simple commands. Command will run using default parameters)
ls
gedit
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.
Code:
ls -l /home
gedit filename.txt
Sometimes an option is also followed by an extra argument or added setting.
Code:
ls --color=always
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.
Code:
ls -al
(This is the same as "ls -a -l")