This is the "A Male Académie ('The Barque of Charon')" by Pierre Subleyras. Painted in the late 18th century, it's a copy of an original work probably created around 1735 by Subleyras himself.
In Greek mythology, Charon was the boatman who ferried souls across the River Styx to Hades, and here we see him in an unusual depiction - as a relatively young man, nude. Unlike literary descriptions, which often portray him with an unkempt beard and squalid clothes.
Subleyras's work belongs to the tradition of the académie, where artists would study the male nude in various poses, like this one, resting on a ledge and holding a pole for support. This was a common exercise in artistic education during that time.
The painting is an académie presented as a subject from classical literature, and it's clear that the artist drew inspiration from his studies of classical sculptures and draped figures. The original work by Subleyras shows more detail and light, but this copy still captures the essence of his style.
A Male Académie ('The Barque of Charon') hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.