Load average is related to the number of processes running and waiting to run.
The load averages differ from CPU percentage in two significant ways:
1) load averages measure the trend in CPU utilization, not only an instantaneous snapshot (as does ...percentage), and
2) load averages include all demand for the CPU not only how much was active at the time of ....measurement.
AFAIK, the three sets of number outputs are the 1-minute, 5-minute and 15-minute average