Complex sentence: The statistic has a chi-squared distribution with two degrees of freedom and can be used to test the null hypothesis that the data are from a normal distribution; since samples from a normal distribution have an expected skewness of 0 and an expected kurtosis of 0.
Split into simpler sentences: The statistic has a chi-squared distribution with two degrees of freedom and can be used to test the null hypothesis that the data are from a normal distribution. Samples from a normal distribution have an expected skewness of 0 and an expected kurtosis of 0.