All the formal details of the picture - medium (what it was painted with, on what - oil on canvas),
At time picture painted 1925 Picasso had already been working in a cubist style, but this particular painting is known to be the one where he can closest to painting in a surrealist style.
There are two types of cubism: analytic - this applies here where the forms are broken down; and synthetic where the figures etc. are built up like in his paintings of the Three Musicians.