Rations are one of the nine major resources and they are needed to feed your party whenever you visit a campsite to prevent them from get hungry or starving. They can be made by using the preserving skill during a shift in the camp to turn meat into rations, they can be bought from merchants, sometimes they can found in containers and if you add the sacrifical bog in the homestead, you get some rations weekly. Every ration has a value of 10 valuables when they are traded.
During sailing, the party does not eat for some reason. When the party sets foot on Brittannia again after a long time of sailing, all party members become hungry or starved the every moment the party moves around.
In the quest Lord of Seals and when you visit the temple of Ribe, you can acquire power and prosperity points for your homestead by giving rations.