To digest a meal, these zymogens are released into the pancreatic duct, and delivered to the small intestine where they are activated by the protease trypsin.
With alcohol abuse it goes like this: alcohol increases zymogen secretion from acinar cells while decreasing fluid and bicarbonate production from the ductal epithelial cells.
That gene encodes for an ion transporter, and mutations in that transporter cause the pancreatic secretions to become thick and sticky, leading to obstruction of the ducts.
When the pancreatic acinar cells are damaged or the the pancreatic ducts are blocked, often because of alcohol abuse or gallstones, the inactive zymogens that the pancreas produces can be prematurely converted to active digestive enzymes.