see what arguments are available for a command
 

When I type ls at the prompt, what argument can I type onto the end so that it will show me all the arguments I can put with ls?

Try reading the man page: i.e. type 'man ls' at the prompt.

Alternatively, most programs have help options, usually -h or --help.

some commands
 

I do not know when it applies, but there have been times when I type a command, and before I type the options I accidenttally hit the return key, it gives me the options in an error response.

Re: some commands
 

This typically applies when the application requires command options. In this situation the program is probably coded to respond in the same way as if you had typed --help or -h.