A man-hour (or person-hour) is one hour of work performed.    From Wordnik.com.  [Citizendium, the Citizens' Compendium - Recent changes [en]] Reference

Between 1923 and 1929, manufacturing output per person-hour increased by 32 percent, but workers 'profits shot up by 65 percent in the same period, and the government let the wealthy keep more of those profits.    From Wordnik.com.  [Firedoglake] Reference