The painting depicts a bacchanal on the Greek island of Andros.
A bacchanalia was a feast honouring Bacchus, the Roman god of wine.
The god Bacchus favoured this island, and one of the streams flowed with wine instead of water.
The painting shows an idealised landscape with the sea in the background.
At the feast, gods and inhabitants of the island drink, dance, and sing.
In the right corner, we can see a naked woman asleep from the effects of wine.
She is a nymph.
A nymph is a goddess of nature in ancient Greece and Rome.