Having full root-level access means that you'll be able to access and change each file on a selected server, which includes all the system files, and to change system settings or set up server-side software which may be needed by specific scripts and even offline applications to function properly. A server is accessed at the root level via a root user, who has full privileges to do all the abovementioned things. The root user can also make other users. For security reasons, you are advised to have a different account for routine tasks and to use the root account only if you actually need to perform a specific task on the hosting server. The root-level access attribute will give you full control of your server from any kind of location, given that you have the user credentials.