What Is To Ring A Cylinder Head???

They could be talking about installing seat "rings". In other words, installing hardened exhaust seats. They are also called seat rings. Ask them to explain what they intend to do and why before committing to it. A good shop will explain things to you. I was a machinist for 10 years and I never had a problem showing customers what I was going to do (or was already doing) to their parts.