Data Cleaning with Pandas - More String Parsing

Hello,

I am studying Data Cleaning with Pandas and I am at this step:

https://www.codecademy.com/paths/data-science/tracks/practical-data-cleaning/modules/data-cleaning-with-pandas/lessons/pandas-data-cleaning/exercises/string-parsing-ii

And I can’t understand why it is 2 and not 0

df.exercise = split_df[2].replace(’[- ]’, ‘’, regex=True)

Is there anybody who can help me?

Thanks!!!