Having full root-level access signifies that you'll be able to access and customize any file on a specific server, in addition to all of the system files, and to change system settings or set up server-side software that may be required by specific scripts and even offline apps to work properly. A server is accessed at the root level via a root user, who has full privileges to perform all the aforementioned things. The root user may also create various other users. For security reasons, you're advised to have a different account for daily tasks and to use the root account only if you actually need to do a task on the website hosting server. The root-level access attribute will give you full control over your server from any kind of location, given that you know the user credentials.