At the counter, pay by simply tapping your card on the POS terminal; wait for a few seconds: once the green light appears and the bip is heard, it means your transaction is confirmed. The printed receipt associated to your payment will be given by the merchant.
A contactless payment can be denied for an amount not exceeding USD 50 or equivalent: the payment is denied for safety reasons and you might be asked to insert your VISA Debit card in the POS terminal to pay.