What are mandays?

That word MANDAYS is actually MAN-DAYS. It means work of one person in the factory for a day.

An industrial unit of production equal to the work one person can produce in a day.

Guys pls explain with the help of an example?

As per the Factories Act

1 Working Day of any Individual (Except Children) is known as 1 Man Day.

"Assuming a man day of 8 hours, you are required to calculate the labour cost per
man day"

This is taken from a revised test paper

Here , man day means : 1 man works for 8hrs in 1 day.

I hope it's correct :)