Having root-level access to your server means that you'll be able to view and modify any file on it, including essential system files. You may also install software which can modify certain settings on the server during the process, so the installation can be done only if you are logged in as the root user. The latter has full privileges, which means that you will have full control over the machine at any time and you can do anything you'd like. You may also create additional users either with identical rights or with fewer rights, based on what you need them for - day-to-day tasks, other server admins, etc. To be on the safe side, it is usually recommended to employ the root account only when you really need it and not for tasks that you can do using 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.