Capacity in Moment gives you the total amount of working capacity available in your company. The total amount of capacity available in Moment is calculated by the amount of working hours in the co-workers schedule times the amount of working days in each week.
The graphs under Resources > Capacity give you different views for the capacity in your company. There are color codes for the different states of the projects on which you have planned hours. In the first two graphs, blue represents the amount of hours planned relative to the entire capacity.
The capacity view only shows the amount of planned hours relative to the capacity, it does not show actually spent hours. This means that the accuracy will depend on your own routines for planning.
Our recommendation is that you plan steadily and at regular intervals. The more you plan, the more accurate will the capacity representation be.