What does this problem mean?

it's very easy to write after understand the problem. The problem is that one man is making something in every day after day.for example he will make something in first day then in third day then in 5th day an so on.you should calculate how many things he will do from A to B. A and B are integers to understand you can think that they are numbers of the day in year.
sorry for mu English.
Regards