This indicator measure the historical skew of actual volatility for an individual security. It measure the volatility of up moves versus down moves over the period and gives a ratio. When the indicator is greater than one, it indicators that volatility is greater to the upside, when it is below 1 it indicates that volatility is skewed to the downside.
This is not comparable to the SKEW index, since that measures the implied volatility across option strikes, rather than using historical volatility.