Having root-level access to a server means that you can view and update any file on it, including important system files. You may also set up software which can update particular settings on the server during the process, so that the installation can be performed only if you're logged in as the root user. The latter has full privileges, which means that you will have full control over your machine whenever you want and you will be able to do anything you would like. You can also make additional users either with similar rights or with fewer rights, depending on what you require them for - everyday 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 that you can do using other accounts. You can 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.