You can get the Volcano when you open up Plot 12 of your Island Farm, which is currently the largest expansion on the Island Farm.
The Volcano produces 4-6 Power every 3 hours, which can be used in the Kitchen to produce dishes on the Seaside Farm or used in the Workshop on the Island Farm.
For more information about the Kitchen, please read 'Game Tips Seaside Farm' > 'Kitchen'. For information on the Workshop, please check 'Game Tips Island Farm' > '[Island] Buildings'.
You will be able to see the Power (Flame) above the Volcano when Power is ready to collect.