Answer :

I wasn't technically sure so i looked it up and found this "In a money summary, each word costs a certain amount. Students are told how much money they have to spend and how much words will cost." So I would say that it is a the cost you have to pay for each word you use ( usally It would not apply to the words a, the and an)  if you to write a certain type of paper. I hope this is of any help.