What does data set data mean?
It has to do with the way data are (are we using "is" yet?) measured.
MEAN means average, MEDIAN means same number above and below, RANGE is how broadly the numbers range. You use different ones depending on what you're interested in calculating. I don't know what MODE is. I just spotted the first two, figured RANGE makes sense in that group, and somehow MODE got attached.
One time we were talking about this at work and a guy explained it by saying that if Bill Gates were to visit our newsroom, our average/MEAN net worth would all go up by millions of dollars. I of course said, "Well then, why don't we invite him?"
So MEAN would be if you add the net worths of everyone in the newsroom plus Bill Gates' then divide by the number of people involved. MEDIAN is, if there are 100 people involved, the amount that would put 50 people on Bill Gates' side. RANGE would be from the lowest net worth in the newsroom to Bill Gates' $120 billion.