This is a trompe-l’oeil, or trick of the eye. It is supposed to look as if a marble bust of Venus has been placed above the door. In order to mislead the viewer, some ‘real’ details have been added: a pink shawl and wreaths of periwinkle.

　This Venus formed a pair with a bust of Adonis (now in Cape Town). They are the only two still-lifes by the history painter Van Everdingen, and they probably hung in his home.

百度翻译：http://fanyi.baidu.com

Trompe l'Oeil：a painting that is cleverly designed to trick people into thinking that the objects represented in it are really there.

错视画：一幅画，巧妙地设计用来诱使人们认为画中所描绘的物体确实存在。