徭役 is a compulsory labor service for the country in ancient China. People who served in 徭役 have to do the work such as building city walls, royal palace or grand cannels. But for some rich people, they can pay money to save them from 徭役. Usually the number of the people who have to serve 徭役 is assigned to different villages. In this context, this village is supposed to provide 1000 men for 徭役，but now they need only to send 500, and the other 500 can be compensated with money.