The table tells you how much food per round that ship produces for you- based on the number of players who are playing in that game. For example, a wooden ship is worth 2 food in a 4 player game, but only 1 food in a 5 player game. Food generated by multiple ships is added up (a player w/ 2 wooden ships in a 4 player game receives 4 food, 2 ea from 2 ships) but the quantity of food you receive from each ship never changes.
Hope this helps!
Thanks for the clarification. It seems like you get less opportunites for food in a 4 or 5 player game. So, why don't they give you more food for each ship in a 4 player game than in a 2 player game (for example)? It just seems like they are making it harder for a larger crowd.