Having root-level access to a server means that you will be able to view and modify any file on it, which includes crucial system files. You can also set up software which can update particular settings on your server during the process, so that the installation can be performed 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 perform anything you'd like. You can also make various other users either with similar rights or with fewer rights, depending on what you want them for - daily tasks, other server administrators, etc. To be on the safe side, it's generally recommended to use the root account only when you actually need it and not for tasks which can be done using 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.