Having root-level access to your server signifies that you'll be able to view and update any file on it, including crucial system files. You can also install software that can update certain settings on the server during the process, so that the installation can be performed only if you're logged in as the root user. The aforementioned has full privileges, i.e. you'll have full control over the machine at any time and you'll be able to do anything you need. You can also make additional users either with the same rights or with fewer rights, according to what you require them for - daily tasks, other server administrators, etc. To be on the safe side, it is usually recommended to employ the root account only when you really need it and not for tasks you can do using other accounts. You can use a web-based graphical interface or a Secure Shell console to be able to connect with the server and to manage it at the root level.