Having full root-level access signifies that you will be able to access and modify any file on a particular server, which includes all of the system files, and to change system settings or install server-side software that may be required by certain scripts and even offline applications in order to function appropriately. A server is accessed at the root level with a root user, who has full privileges to do all of the abovementioned tasks. The root user may also make various other users. For safety reasons, you're advised to have a separate account for day-to-day tasks and to use the root account only if you actually need to do some task on your server. The root-level access feature will give you full control over your server from any existing location, as long as you know the user credentials.