Do you mean the arrow you can click on and off? When it's on that means the Repeat will stop repeating as soon as an instruction fails. For instance if it processes a "Find Nearest Log" instruction but can't find any it will stop repeating.
At the moment the Folk are just an experiment we've been trying to see how they fit in. The only reason to feed and wash them would be to see how many you can keep happy. In the next version they'll have a much more important role to play :)
