Having root-level access to your server signifies that you'll be able to view and update any file on it, including important system files. You may also install software which can modify particular settings on the server during the process, so the installation is possible only if you are signed 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 can perform anything you would like. You can also generate various other users either with identical rights or with fewer rights, based on what you want them for - everyday tasks, other server administrators, 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 you can do via other accounts. You can 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.