Your last five customer interactions lasted 2,3,6,8 and 4 minutes that means i've averaged how many minutes across those five interactions ?

We are given different amount of time that a customer interacted with a person (you) and we asked to get the average of those time.
Simply, we add all the data and divide it by the total number of data.
So,
average = (2 + 3 + 6 + 8 + 4) / 5
average = 23 / 5
average = 4.6 minutes