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 may also set up software that can update certain settings on the server during the process, so that the installation can be done only if you're signed in as the root user. The aforementioned has full privileges, which means that you'll have full control over your machine whenever you want and you can do anything you would like. You may also make additional users either with similar rights or with fewer rights, based on what you require them for - daily tasks, other server admins, etc. To be on the safe side, it's generally recommended to use the root account only when you really need it and not for tasks you can do via other accounts. You may use a web-based graphical interface or a Secure Shell console in order to connect to the server and to manage it at the root level.