please explain mad thank you

MAD stands for mean absolute deviation.

To find the mad, first find the mean of the data set. Next find the absolute difference between the mean and all of the pieces of data. Then find the mean of the differences to get the mad.

https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-data-statistics/cc-6-mad/v/mean-absolute-deviation