You can connect (or park) a domain name to your website. Actually, you could park more than one, if needed. Go to your website, click in the admin bar "Settings" and then "Domains and Email". You will see all domain names to your site, and you can add a new one.
Before the domain name will link up, you will need to set the domain name name servers to these settings:
Once this is complete, then you will be able to park that domain name to your site. You can also manage your email settings to point your domain name to an email provider of your choice.