Contactless refers to the fact that it is a wireless device.
A payment is contactless when you don't insert your credit or debit card at the checkout. Instead, you hold your card within five centimeters of the terminal and your payment information is sent wirelessly and processed. Contactless cards offer a faster and more convenient alternative to cash for low-value purchases at fast food restaurants, convenience stores and transport terminals. They are also ideal for remote or unattended payment situations, such as vending machines, road tolls or parking meters.
Contactless payment is catching on in a big way with the United Kingdom and France. Plus, in China, more than 80% of Hong Kong consumers are making contactless payments today. Transport use is popular as demonstrated in the UK by Barclays employing the Oyster metro product on its Oneplus credit card.