You can enter text commands in your terminal (or shell, to be more specific).
command
Some commands take arguments. These could be file names, folder names, or strings:
command argument
Some commands can take multiple arguments:
command argument-1 argument-2
Some commands also take options that start with a dash. They are usually a lowercase letter, uppercase letter, or number.
command -a
You can also use multiple options, like this:
command -a -b
You can put them together, like this:
command -ab
You can use options and arguments together:
command -ab argument
command -ab argument-1 argument-2