Do you mean what you do to learn python or what you do with python?
If it's the former, there's tutorials at the main Python site. There's a free book I found very helpful: Think Python.
If it's the latter, only you can answer that question!
Please note that you should learn Python 3 unless you have a very specific need to learn legacy python (Python 2). At the link for the Think Python book mentioned by Joe Ess there is a version of the book specifically for Python 3.
Python 3 is where all the new development and features are added. Legacy python is only getting bug fixes and will be "end-of-life"d in 2020.
I used Enthought CanopyIDE for Python, free and easy to use. I'm sure there's many Youtube videos out there about it too.
Also, if you want learn Python through your phone, there's an app called SoloLearn. I have personally been using it to relearn Python myself. It's also free and there's many different coding languages you can learn on there.