The video is about how to find the variance of the set of data. They found the variance by using the variance formula. Variance formula was represented by square of S, whereas S is the Standard Deviation.
Variance is got by the summation of the difference between the average of the set of data and each data divided by the number of total samples given.
They explained with an example by taking 6,3,8,5 and 3 as samples. By substituting the samples they found the final variance as 4.5.