what does linux load average mean?

ok first how can we get load average info from linux
use uptime cmd also you can get that info by top cmd
the output will be:
19:11:40 up 6 days,  3:04,  2 users,  load average: 5.55, 3.17, 2.34

the load average have three numbers each numbers mean 1min,5mins,15mins
and the definition of load average is:
the load average tries to measure the number of active processes at any time. As a measure of CPU utilization.