Is NaBr and KBr a buffer?

No, NaBr (sodium bromide) and KBr (potassium bromide) are not buffers. They are both salts that dissociate into their respective ions in solution, but they do not contain a weak acid and its conjugate base or a weak base and its conjugate acid, which are required components for a buffer system. Buffers work to resist changes in pH upon the addition of acids or bases, which NaBr and KBr cannot do.