how to know the day is it Monday Tuesday or of a specific date in Python

Question

I have a pandas dataframe with one column called "date" with dates from 10/1/2018 to 5/1/2020 and one column called "sales" with total sales of the day. I set "date" as index and I want to have another column to show the day of the dates (e.g. Monday, Tuesday, Wednesday...). Is there any dataframe function to do that?

Thank you.