Learn Python

Official Beginner's Guide: https://wiki.python.org/moin/BeginnersGuide
Official Tutorial: https://docs.python.org/3/tutorial/

Shortcuts:
https://wiki.python.org/moin/BeginnersGuide/NonProgrammers
https://wiki.python.org/moin/BeginnersGuide/Programmers

Videos:
PyCon (2015 - current)
https://www.youtube.com/user/PythonItalia [EuroPython]

Learn Python:
https://automatetheboringstuff.com/ (for complete beginners to programming)
https://learnxinyminutes.com/docs/python3/ (for people who know programming already)
https://docs.python.org/3/tutorial/ (official tutorial)
http://python.swaroopch.com/ (useful book)
http://www.codeabbey.com/ (exercises for beginners)

For a longer and opensource list of python resources, https://github.com/bitsacm/Slack-Stock-DAG/blob/master/python.md