A Giffy code is a 19-digit code starting with 6064 36, with a matching PIN. You usually receive it by e-mail, sometimes on a physical card, for example from your employer or another organisation.
With your Giffy code you choose a gift card from a brand yourself in the Giffy Store: store.ilovegiffy.com/products, or the store mentioned in your e-mail. You then receive that gift card by e-mail, with its own card number and PIN. Only that card number and PIN are used at the retailer; your Giffy code does not work there.
Your Giffy code is valid for 24 months from the date of issue. The Gemeente Westland Cadeaubon is valid for 36 months.
Please note: a card number starting with 6064 3636 is not a Giffy code but already a bol.com gift card. You use it directly at checkout on bol.com.