Labor units and Remaining units

Hi everyone,

I am new in primavera, and I am just confused about the numbers where you can see to remaining units and remaining labor units, now my question is "is the remaining unit or the labor units" is the duration of time or a number of people or number of days This is in resources,,I am going to attached some photos so that somebody can understand my question..any help is much appreaciated,,

Thanks a lot,,