root is the superuser of the system, similar to an administrator on a Windows system.
When a command is executed by root, it bypasses all of the usual integrety checking done on other users, so a root user can install software, kill processes or other housekeeping tasks that regular user (or a non-root intruder) should not be able to do.
You can switch to a different virtual terminal at any time, Ctrl+Alt+F1 will take you to a text console and Alt+F7 will take you back to terminal 7, which is usually used for X-Windows (your graphical user interface).
The easiest way to run a script as root is just to open a terminal (Ctrl+Alt+F1, or start a termal emulator program like konsole or xterm), and then log in as root (with your root password) or type "su --login" to switch to the root user (again, entering your root password).
Hope that makes it clearer,
— Robert J. Lee