It is the standard deviation divided by the mean (the worksheet reports the quotient, it does not convert the value to a percentage). The coefficient of variation is a dimensionless measure of variation. This statistic is not defined for the case of a zero mean. In fact, this measure is only useful when dealing with strictly positive data.
Population Coefficient of Variation (V)
Sample Coefficient of Variation (V)
where
S 

See Also
95% and 99% Confidence Interval for the Mean
Critical Value of KS Statistic at 90%, 95%, and 99% Significance Level
KolmogorovSmirnov Goodness of Fit Statistic for Normal Distribution