This is an Arduino LPG gas sensor. It has MQ5 probe which is very sensitive with LPG, natural gas, town gas. It is less sensitive with alcohol, cooking fumes and cigarette smoke.
The sensitivity can be adjusted by the potentiometer. The output is proportional to the density of gas. You can use analog reading to read the data from this sensor.
To ease the difficulty of using this sensor, a Gravity Interface is adapted to allow plug&play. The Arduino IO expansion shield is the best match for this senor connecting to your Arduino.