An audiogram is the result of a hearing test and it shows you the extent of any hearing loss in either ear.
During a hearing test you are tested for your ability to hear different tones and these are plotted from left to right on the audiogram, low pitch tones on the left, moving to high pitch sounds on the right.
As each tone is tested, the point at which you can hear it is also recorded. This is top-down and measured in decibels, quieter sounds at the top and louder at the bottom. So, if your audiogram shows a straight line across the 10 decibel line then you have very, very good hearing.