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