The hosted domains feature of a web hosting account denotes the number of registered domains which you can include within the same account. Registering a domain name and hosting it are 2 totally different services even though many people consider them to be the very same thing. While the registration means that you become the owner of a given domain, the hosting part is what really enables you to have a site considering that this is where your data and email messages will be. Since these are two independent services, you can register a new domain name with one company and host it with another by changing its name servers (DNS) - the domain shall work in the exact same way just as if it was registered and hosted with the same company. It's also extremely important to know that changing the hosting means directing the domain to a different company and not transferring it.