Python is a computer language that you can use on the Pi.
Coursera is offering a free course 'Programming for everybody (Getting started with Python)'.
I have signed up for this class and can preview the first week now.
I think you have until Oct 27 to sign up for it.
https://www.coursera.org/learn/pythonI downloaded the Raspian Jessie OS and burned it to an extra micro sd card, switched it out of my new Bride of Frankenstein (NES) and am now using the GUI OS and playing around with Python. When Im ready to play games I can just switch the cards back and have the retropie back on the system.
Raspian Jessie comes with Python V 2.7.9, I think the class suggests using V 3, so i may have to download it.
I plan to use this Pi setup for my class, however you can download Python for Windows or Linux, so you dont have to have a Pi to take the course.
Edit: just found that raspian jessie also comes with python version 3. Just type python3 at the terminal prompt.