The hosted domains feature of a website hosting account refers to the number of registered domains which you could add in the very same account. Registering a domain address and hosting it are 2 different services although many people consider them to be the exact same thing. While the registration means you become the owner of a specific domain, the hosting aspect is what really permits you to have a site because this is where your files and emails will be. As these are 2 different services, you can register a new domain name with one company and host it with another by modifying its name servers (DNS) - the domain address shall work in the exact same way just as if it was registered and hosted using the same company. Also, it is extremely important to know that changing the hosting means directing the domain to another company and not transferring it.