What is meant by the saying?

pls expain i m not able to understand it.

First let us think of work volume. As you wish it may be very bigger work that definitely one man can take 100 days to complete. You got the Idea of getting help from others. Everything arranged, the number of men involved is risen to 100. The result is surprising. How? 100 days work completed by 100 men in one day. They made it very light. Heavy work made light by unity of hands in single jerk.

My guess is that the more people that pitch in and help with a job, the less work there is for everyone to do. Know what I mean? You divide up the tasks and have an equal amount of things for each person to do and it'll all get done faster.