It is only one account in pesos. The Debit card is linked to that account and can be used with funds directly taken from the peso account. A US Dollar account would be a second account.......The OP mentions receiving a passbook and a debit card. If this means having two accounts, and both are in pesos, keeping most of the money in the passbook account would lessen the fraud/theft concern, as the debit card is what is most commonly exploited.