Having full root-level access signifies that you will be able to access and change any file on a particular server, which includes 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 work appropriately. A server is accessed at the root level with a root user, which has full privileges to perform all of the abovementioned things. Your root user may also generate various other users. For safety reasons, you're advised to have one more account for day-to-day tasks and to use the root account only if you actually need to do some task on your hosting server. The root-level access attribute gives you full control of your server from any location, given that you have the user credentials.