Having full root-level access signifies that you will be able to access and modify any file on a selected server, including all the system files, and to change system settings or install server-side software which may be required by specific scripts and even offline apps to function properly. A server is accessed at the root level via a root user, which has full privileges to do any of the aforementioned things. Your root user can also create various other users. For safety reasons, you're advised to have one more account for routine tasks and to use the root account only if you actually need to do a specific task on the hosting server. The root-level access feature provides you with full control of your server from almost any location, given that you know the user credentials.
