Having full root-level access means that you can access and change every file on a specific server, in addition to all of the system files, and to change system settings or set up server-side software which may be needed by certain scripts and even offline apps in order to function properly. A server is accessed at the root level via a root user, which has full privileges to do all the aforementioned things. The root user may also generate other users. For security reasons, you're advised to have another account for routine tasks and to use the root account only if you actually need to perform a particular task on the server. The root-level access feature will give you full control over your server from almost any location, provided that you have the user credentials.