I'm going through the OpenShift-documentation right now and I stumbled over the word "backing pod".
The google-search for "backing pod" has exactly four entries and all of them refer to the same line of text.
Is this just a backup pod? Or is it a copied pod for redundancy?
It's likely meant to be "the pod that is running your app / code / database". "Backing" is used in the context of a backer - someone (the pod) providing support for a task (the service).
It should probably just say "the pods that are part of the service".