Complex sentence: The main source of revenue comes from Coffee that is grown in the mountainous regions of the province, and during the coffee harvest, there may be roadblocks, where soldiers ensure that the coffee is delivered to the government and not the black market.
Split into simpler sentences: The main source of revenue comes from coffee that is grown in the mountainous regions of the province. During the coffee harvest there may be roadblocks, where soldiers ensure that the coffee is delivered to the government and not the black market.