It means you need to go to command line and start typing commands (or copy/paste them)4
Hit the super key to open Dash and type "terminal"
and you will see something similar to this:
and you can start typing commands.
There are 4 methods to get to a command line when using Unity:
- Dash -> Search for Terminal
- Dash -> More Apps -> 'See More Results' -> Terminal
- Dash -> More Apps -> Accessories -> Terminal
- Keyboard Shortcut: Ctrl + Alt + T
For more information I would suggest reading this wiki page:
Why use the command-line?
"Under Linux there are GUIs (graphical user interfaces), where you can point and click and drag, and hopefully get work done without first reading lots of documentation. The traditional Unix environment is a CLI (command line interface), where you type commands to tell the computer what to do. That is faster and more powerful, but requires finding out what the commands are."
-- from man intro(1)
The wiki page has a list of the most used commands (like how to change or list a directory, copy or remove files, but also explains how to find commands and how the manual works.
Here is a list of Bash commands but most of us will probably not know them all ;)