Information about data frame:

Names of columns, data type for columns, number of columns ...

What unique years are in this df?

What is the second most popular payment method for this data frame?

Find the most popular category in column "category_name_1":

Find the most popular sku in the sku column:

Find the most popular product in sku column where name contain word "iphone":

Question 1. Find "Customer ID" which made the most purchases?
Question 2. How many rows contain this "Customer ID"?

Answer 1: 85775
Answer 2: 2535