You can see the Volcano when you open Plot 12 which is currently the last expansion of 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 can be used in the WorkShop on the Island farm.

For more information about the Kitchen, please read FAQ 'Kitchen' and about the  Workshop, please read FAQ '[Island] Buildings'

 

You will be able to see Power (Flame) above the Volcano when the Power is ready to collect.