The page Daniel is working from: http://wd15.github.io/python-novice-gapminder/
Here’s the direct link to the part of the lesson on using the Pandas library with the Jarvis data. This was the really meaty part of his session where he worked first with a subset of the Jarvis data and then with the whole dataset. Follow it here: https://wd15.github.io/python-novice-gapminder/08-data-frames/index.html
Pandas was written by Wes McKinney. He has an excellent book you might want to check out. It is also often available for online reading from University libraries or you can check it out here: https://smile.amazon.com/Python-Data-Analysis-Wrangling-IPython/dp/1491957662/ref=sr_1_3?ie=UTF8&qid=1542052897&sr=8-3&keywords=pandas+python&dpID=51AGrudlIhL&preST=_SX258_BO1,204,203,200_QL70_&dpSrc=srch
You can also look for good YouTube videos of Wes McKinney talking about Pandas at various meetings.