Newbie question flow meter

Just ordered the arduino, Swiss flow meter and the raspberry pi. Looking over the directions and I see I plug the flow meter into pin 2, correct? What about the other wire from the flow meter pin 12? Any other tips that can help? Thanks

typically, flow meters will have 3 wires.
power (red), ground (black) and signal (usually yellow). i believe you have to use pins 2 and 4 on the arduino for the signal wires. the power can be plugged to a 5v source and the grounds to a ground pin.