If i call uptime on my server via shell i get string like this:
# uptime
22.23.23 up 5 days, 51 min, 3 users, load average 34.32 16.08 5.07
what does this part mean load average 34.32 16.08 5.07 exactly –
why three digits? does it mean three cores or what?
They are the load averages over the last 1, 5, and 15 minutes, they are not related to your cores.
From the man page:
For more information see man uptime.