This is "A Dune Landscape" by Willem Buytewech the Younger, a Dutch painter. Painted in the mid-seventeenth century, around 1660 to 1670, it's one of only a few surviving works from his hand. Born in Rotterdam, he seems to have been active as both a landscape and figure painter.
In this painting, you see a man sitting on a fallen tree, with sheep and goats grazing ahead of him. Beyond them, two small houses are almost lost in the stunted trees, while the dunes stretch out towards the sea beneath a broken sky. The artist combines landscapes and figures in a single scene, which was not uncommon during this period.
The man's dog looks up at him, and his grey horse waits patiently for him to continue his journey. But what's interesting is that the horse has a heavy collar but no stirrups – it might have been harnessed to a cart or wagon. On one side of the central group, you see a large, broken wheel, which could be part of the story being told.
The work was actually once attributed to Jan Wijnants, another Dutch painter known for his dune landscapes. However, it's now recognized as a genuine Buytewech. His paintings are rare, so we're fortunate to have this example in front of us.
A Dune Landscape 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.