Having root-level access to your server signifies that you will be able to view and update any file on it, including essential system files. You may also install software that can modify certain settings on the server during the process, so the installation can be done only if you are signed in as the root user. The latter has full privileges, which means that you will have full control over the machine whenever you want and you will be able to do anything you'd like. You may also make additional users either with similar rights or with fewer rights, based on what you need them for - everyday tasks, other server administrators, etc. To be on the safe side, it's usually recommended to use the root account only when you really need it and not for tasks that you can do through other accounts. You may use a web-based graphical interface or a Secure Shell console in order to connect to the server and to control it at the root level.