This image depicts the Hindu Gods Vishnu and Shiva combined into one form: Hari Hara, the supreme God.
The right half of the image depicts Shiva. His skin is grey from the ashes that he smears upon himself and in the middle of his forehead is his third eye. On the left is Vishnu, who sports a peacock feather crown and blue skin, symbols associated with Krishna, Vishnu's eighth incarnation.
The deity's cult dates back to the sixth century and was patronised by the rulers of the Vijayanagara kingdom between the 14th and 16th centuries.
This image is an example of Kalighat painting, a distinctive style of painting from Kolkata.