Flying Wedge Notation:

This notation is used in stereo chemistry to describe the three dimensional shape of an organic molecule. The carbon atom lies in the plane of the white board and so do the two hydrogen atoms joined by straight lines. The lined wedge lies at the back of the Board and the black shaded wedge lies to its front.

Here is a link to help you understand this concept with a few more examples : Flying wedge Notation.

"Structure of methane shown in a flying wedge notation"