Labour productivity indicates how much economic production is associated with one worker or one hour of work. A standard macroeconomic measure uses GDP at constant prices as the output measure and relates it either to total employment or to aggregate hours worked. The denominator determines the interpretation: employment-based figures show output per worker, whereas hour-based figures show output per hour.
Source: European Central Bank (ECB) (source). This glossary entry is an independently worded adaptation of the cited information.