The variance and standard deviation of excess return are simply variance and standard deviation applied to the excess return series e1, ... , en.
Var(e1, ..., en) = 
StdDev(e1, ..., en) = 
AnnStdDev(e1, ..., en) = StdDev(e1, ..., en) * 
Standard deviation of excess returns measures the deviations of an excess returns series from its mean.
Related Statistics:
Annualized Excess Return
Cumulative Excess Return
Information Ratio