At first you can see, that this is a violin concerto of Alban Berg. The spectrogram shows 6 seconds of the sound after a fourier transformation. The y axis is the pitch level, the x axis the time and the power of the frequencies is displayed as color - most likely red for high power and blue for low power. Actually there should by a colormap to define the absolute values.
On the bottom there are some strange marks, perhaps a three-quarter time.
Did you search in the net for explanations already? Maybe WikiPedia: Spectrogram can explain this better than me.
