It´s 23 additional VMs based on average utilization of your existing VMs.  /Mattias
I have downloaded the vKernel vOPS vApp and see on the Environment Explorer page the capacity box on the right shows "You have room on 1 cluster to place up to 23 VMs". Does this mean that is the maximum VMs or does that number indicate there is capacity for 23 more VMs?
How to tell how many more VMs can be added to a host or cluster?