Having full root-level access means that you will be able to access and modify every file on a specific server, which includes all system files, and to change system settings or install server-side software which may be needed by certain scripts and even offline apps in order to work effectively. 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 may also make various 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 do a specific task on the website hosting server. The root-level access attribute will give you full control over your server from almost any location, as long as you have the user credentials.
