Petert4522.....Thank you for that. Your reply pushed me in a different direction and I believe I have it figured out.
General Interbank Recurring Order (GIRO) is an automated electronic payment service which allows you to make monthly payment to the billing organization (BO) from your bank account directly. The amount will be deducted from your DBS or POSB account and paid to your BO every month, upon the BO's request.
I am guessing that after the auto payment came out of your account, the bank made up a receipt or something and put those stamps on it. The snip I added here is an example.