Some further examples: Jane spent $100. Where did the money go? Petrol accounted for $50 of the money spent. Lunch accounted for $20. A birthday present accounted for $30. Now try this: We will lose 100 jobs soon. Why? Lower profits account for 25 of the job losses. Wastage accounts for another 50. And higher wages accounts for the last 25. I hope it is clear now.

Another way of saying your sentence would be: the non replacement of departing staff: a gradual reduction in the work force of an organization achieved by not replacing employees who leave through retirement or resignation.

account for = to be the reason for I think jobs = job losses. There are going to be job losses, and the reason for some of the job losses is the wastage over that period of time.

yeah i think you are right .Because i also think so.