Picard: The economics of the future are somewhat different. You see... money doesn't exist in the 24th century.
Lily: No money? You mean, you don't get paid?
Picard: The acquisition of wealth is no longer the driving force in our lives. We work to better ourselves...
Picard trying to explain, to her question about how much this ship cost, that the economics of the future are different. He explains that money does not exist in the 24th century. Lily cannot believe that there is no money involved and that they don't get paid. Picard explains that the acquisition of wealth is no longer the driving force but working to better themselves is.