This painting is called Guitar on a Chair. The artist that painted this painting is Juan Gris. He created this piece in 1913 in Spain. This style of painting is known as synthetic cubism. He painted this with oil on canvas.
Juan Gris (1887 - 1927) | Synthetic Cubism | Still Life with Bottle and Cigars - 1912 || Synthetic Cubism is the late phase of cubism, characterized chiefly by an increased use of color and the imitation or introduction of a wide range of textures and material into painting.