I honestly it's a bit over people heads, including mine. Cash and card, is a no brainer, you pay for the goods or service by handing over cash or paying by card.
Even PayPal is easy to understand, its an online account that you link with your bank account and credit card to pay for goods online. Having said that, i wouldn't have a clue how to pay with PayPal in a store.
As for BitCoin, until they can make it easy for the average person to grasp, it won't really take off as a payment method.