Pro Tip: Click here to look at your orders and check how much you've spent on Amazon.com this month. Payments to the 'Amazon Marketplace' on your bank statement are orders, subscriptions or digital device purchases.
The 'Amazon Marketplace' title on your bank statement shows how much you've spent on Amazon.com. All your orders that get their transactions approved deduct money from your account.
Your bank statement reflects these payments back to you. It does this by showing you the amount you've payed to the Amazon Marketplace.