The field names are taken directly from the form and can be seen in full when you hover your mouse over them.
However, we would recommend changing them to something more easily visible and identifiable to yourself like 'Card Holder Name' or 'Email'.
You can edit the field names by Add Label button next to the field name in the 'Popular Drop Off' report then entering what you would like the field to be called.
All you need to do is click save, and it will display like this across all of our reports.
If you are unable to identify the field from it's name or ID you may have to search for for the field ID/name in the HTML of your form. For more instruction on how to view and search the HTML of your form see this article on how to find your Form name and ID.