Having full root-level access means that you will be able to access and modify any kind of file on a selected server, in addition to all of the system files, and to change system settings or install server-side software which may be required by specific scripts and even offline apps in order to function appropriately. A server is accessed at the root level through a root user, which has full privileges to do all the aforementioned things. The root user may also create other users. For security reasons, you're advised to have a different account for everyday tasks and to use the root account only if you actually need to perform a task on your hosting server. The root-level access feature provides you with full control over your server from almost any location, provided that you know the user credentials.
