The hosted domains feature of a hosting account refers to the amount of registered domain names which you could include within the very same account. Registering a domain address and hosting it are 2 different services although a lot of people consider them to be the very same thing. While the registration ensures that you become the owner of a given domain, the hosting part is what really permits you to have a website as this is where your data and e-mails are going to be. As these are 2 separate services, you can register a new domain address with one company and host it with another by changing its name servers (DNS) - the domain address is going to work in the exact same way as if it was registered and hosted with the exact same company. Additionally, it is very important to know that changing the hosting means pointing the domain address to a different company and not transferring it.