pandas - how to access cell in pandas, equivalent of df[3,4] in R

You can use iloc (to get by position):

df.iloc[3,4]

I recommend reading the indexing section of the docs.

If you want to access the cell based on the column and row labels, use at:

df.at["Year","Temperature"]

This will return the cell intersected by the row "Year" and the column "Temperature".