Worker groups are a collection of XenApp servers.
A worker group can contain any number of servers from the same farm it belongs to. It can also be empty. A server can belong to different worker groups.
With worker groups you can:
To create a worker group, right-click on the Worker Groups node in Citrix AppCenter, and select Create worker group.
You need to give a name to the new worker group, an optional description, and select the source of the servers: