The default behavior for a command may usually be modified by adding a -- option to the command. The ls command, for example, has a -s option so that ls -s will include file sizes in the listing. There is also a -h option to get those sizes in a "human readable" format.

Options can be grouped in clusters so

ls -sh

is exactly the same command as

ls -s -h

Most options have a long version, prefixed with two dashes instead of one, so even

ls --size --human-readable

is the same command.