The average or the Mean filter corresponds to the arithmetic average/mean. Average = 1/n*(x1+x2+x2+...+xn). With the laser line triangulation, this filter is used to "smooth" the profiles. To some extent, the Noise is suppressed. Significantly deviating values change the result clearly.
Example: 3;5;6;10;27 --> Average = 10.2
If the outlier "27" should be less considered in the result, the values can be corrected using the Mean filter.