It is not a rate like “men per hour” nor the “amount of work done per person per hour”.
Rather, the “man-hour” is a unit, used to compare the amount of “work” done by a person working constantly for an hour, against other tasks to be completed:
number of people × number of hours = man-hour
The man-hour is definitely related to the rate of “amount of work per person per hour”, as we will see.
The concept of “man-hour” can make it easier to calculate the resources required for a project-which is why it is widely used in project management to estimate the time and money required for various tasks.