Having root-level access to a server signifies that you will be able to view and modify any file on it, which includes important system files. You can also install software which can update particular settings on your server throughout the, so that the installation can be done only if you're logged in as the root user. The aforementioned has full privileges, which means that you'll have full control over your machine at any time and you will be able to perform anything you need. You may also generate other users either with the same rights or with fewer rights, according to what you need them for - everyday tasks, other server administrators, etc. To be on the safe side, it's 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 to connect with the server and to control it at the root level.