If you have root-level access to a hosting server, this means that you'll have full control over it. In other words, you can set up any server-side application regardless of the changes that it will make to the software environment on the server, and you can both access and modify any kind of file, including system files, and modify various settings. This can be done by connecting to the server as a root user which has full privileges to do the aforementioned things and also to generate other users, including users who also have full privileges. This connection can be established through a web-based graphical interface or a Secure Shell console. For safety reasons, it's recommended that you create one more user for your daily work and employ the root user only when you need to customize the server or to set up software which may be required by some script-driven application that you'd like to run.