You can have more than one domain pointing to your site. There are issues with that - you do not want "duplicate content" as Google does not like that. However, there are many advantages too, and you can point other domains to their own space in your hosted package.
You can also add subdomains. if you own domain.com, and you want to add a news area, you could create news.domain.com - this will keep the statistics separate, and allows clear separation between areas of your site.
You can add a new domain name to your site, and have it show the content of a sub folder on your site. This can sound confusing, but as you work through it, it gets easier.
A sub domain is just another way of separating areas of your site. you could have domain.com - your main site, support.domain.com - where your support pages are and dev.domain.com, where you are building your next site.
You can use an alias to have domain2.com automatically show the content on domain.com. This only affects web access, not emails.
You can point one domain to another. Unlike an alias, it can also be set as a temporary or permanent redirect, to update search engines and bookmarks.
Simple Zone Editor
If you need to update your dns, this is the place. You should not play here unless you know what you are doing. Main reason for using this would to be point a sub domain to your office IP for development work