The M-Score was created by professor Beneish. It uses eight financial ratios to identify whether a company has manipulated earnings. In 1998, students from Cornell University University correctly identified Enron as an earnings manipulator using the M-Score, where experienced financial analysts failed to do so. (Enron filed for bankruptcy in late 2001.
The M-Score is displayed in a bullet chart. A score above -2.22 indicates a strong likelyhood of earnings manipulation.
If you want to understand how the M-Score is calculated, you can click on the details link at the top right corner of the Beneish M-Score panel. This opens the M-Scorecard.
This scorecard shows all 8 signals used to calculate the score and an explanation in plain English. You can drill down on a particular signal and see how it's calculated.