Most of our packages allow you to host unlimited domains on yuor account.
You can add domains both as addon or parked domains.
Addon domain is a separate site with its own content managed by same cPanel as your main domain, pointed to public_html/addon-domain-directory.
Parked domain is pointed to public_html and shows the same content as your main domain. Obviously main domain is also pointed to public_html.
You can add both addon and paked domains in your cPanel control panel ( Main->Domains section).