If I received a Certificate of Release of Federal Tax lien, what does this mean?

The certificate of release for a federal tax lien should list the tax year(s) that were released. This document means that the balances for those years were resolved, either due to you satisfying the lien via payment, or due to the statute of limitations for collection expiring. Although the lien is released, it will remain on your credit history as a negative item unless you apply to have the lien withdrawn.