The Farmhands are a group of workers in Agricola: All Creatures Big and Small.
The Farmhands are incredibly useful, as they are your assignable workers. They can be assigned to plots of land in order to carry out actions. Actions cannot be carried out without a farmhand attached or a passive action being defined. Farmhands are also used to collect certain kinds of resources, and to manage these resources on the farm.
Think of the Farmhands as the "go between" for the player and the play space. All actions are undertaken using the Farmhands, who are a direct extension of the player.