Is the Marriott Bonvoy Debit Card a bank account?

No, your Card is a Direct Debit based card that works as a layer in front of your current bank account to make earning Marriott Bonvoy Points simple.

By partnering with your existing bank account, you don’t need to worry about prepaying, topping up, and managing a new bank account. You use Marriott Bonvoy Debit Card and Marriott Bonvoy Premium Debit Card just as you would your existing debit card.