Having root-level access to a server signifies that you will be able to view and modify any file on it, including crucial system files. You can also set up software that can update particular settings on your server during the process, so the installation can be performed only if you are signed in as the root user. The latter has full privileges, i.e. you'll have full control over the machine whenever you want and you will be able to perform anything you'd like. You may also generate various other users either with the same rights or with fewer rights, depending on what you need them for - daily tasks, other server admins, etcetera. To be on the safe side, it is usually recommended to employ the root account only when you actually need it and not for tasks that you can do via other accounts. You may use a web-based graphical interface or a Secure Shell console in order to connect with the server and to manage it at the root level.