The use of adverts on a parked web domain to generate revenue when the domain is otherwise idle is known as domain parking, or cash parking.
You earn money based on how many users visit your site and click on the commercials, similar to affiliate marketing.
The method of running many "virtual" web servers on a single physical host computer is referred to as virtual web hosting. A single machine can host thousands of independent websites using this method.
Credit cards, bank transfers, and PayPal are the most common payment methods accepted by hosts.