Having full root-level access means that you will be able to access and modify every file on a particular server, in addition to all of the system files, and to change system settings or install server-side software which may be required by certain scripts and even offline apps to function efficiently. A server is accessed at the root level through a root user, which has full privileges to perform any of the aforementioned things. Your root user can also create various other users. For safety reasons, you are advised to have a different account for day-to-day 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 provide you with full control over your server from any location, provided that you know the user credentials.