The hosted domains feature of a web hosting account indicates the number of registered domain names that you can add in the same account. Registering a domain name and hosting it are 2 totally different services even though many people consider them to be the same thing. While the registration means you become the owner of a specific domain address, the hosting part is what in fact allows you to have a website considering that this is where your data and e-mails are going to be. Since these are 2 separate services, it is possible to register a new domain name with one company and host it with another by changing its name servers (DNS) - the domain name is going to work in the exact same way just as if it was registered and hosted with the exact same company. It's also very important to know that changing the hosting means pointing the domain name to a different company and not transferring it.