This is a harpsichord (clavecimbel in Dutch) with a painting on it by Joop Moesman (1909-1988), a Dutch painter who is famous for his works in surrealistic style. It is part of the collection of The Nijenhuis Castle and museum De Fundatie.
The harpsichord produces sound by plucking a string when a key is pressed. It was widely used in Renaissance and Baroque music. During the late 18th century, it gradually dissappeared from the musical scene with the rise of the piano.