Having full root-level access signifies that you can access and update every file on a specific server, which includes all of the system files, and to change system settings or install server-side software which may be needed by specific scripts and even offline apps in order to work efficiently. A server is accessed at the root level through a root user, which has full privileges to do any of the abovementioned things. Your root user may also create 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 perform some task on the hosting server. The root-level access feature provides you with full control of your server from any kind of location, given that you know the user credentials.