If you want to convert a date to the weekday, you can use the Text Function to return a text string. Otherwise, please check how to convert a date to the day number.
To convert a date to the weekday with 3 letters (e.g., Mon), please copy the formula and change the cell name.
=Text(A1,"DDD")
To convert a date to the weekday with all letters (e.g., Monday), please copy the formula and change the cell name.
=Text(A1,"DDDD")
Alternatively, please follow the steps below to format the date into the weekday.
Step 1: Select the date range and click the "Home" tab from the ribbon;
Step 2: Click the right bottom corner in the "Number" group;
Step 3: In the "Format Cell" window, click "Custom" and type "ddd" in the type box for the week name with 3 letters or "dddd" for the week name with all letters;
Step 4: Click "OK".
