In this video tennis balls are used to explain encryption without any jargons.
Wireless Encryption Protocol WEP is not permitted under PCI DSS as a mode for transmission of card data. See a demonstration of WEP being cracked. Usage of WEP has been identified as one of the biggest threats to card data security.
Under PCI DSS requirement 4, card data must travel in public network encrypted. SSL is an approved method. This video gives an introduction to SSL.