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