How to calculcate "person-days of work"

A person day of work is equivalent to 8 hours of work. This data is collected at a project and site level based on what activities take place at which level. For example, work that spans the whole project, such as nursery activities, is reported at project level, while site specific work such as planting and site maintenance is reported for each site. The workday data is also disaggregated by paid/volunteer, gender, age, and ethnicity.

Please see the attached resource for more details.