In Team Foundation Server, labels are similar to tags in other version control system; a label contains files at a specific version.
When we release some product, we snapshot the entire team project as a label - that is to say that we create some label 11_Release
to point to our 11.0.0 release, and it will contain $/TEE
(our Team Project) at version Latest. We then unthaw the branch and allow check-ins to proceed.
Exactly how this works will depend on your process, of course. You need not necessarily apply the latest version to that label, it could, in fact, be some other changeset or even date version spec.