What kind of "bar" are you talking about?
Either a couple of Brackets on the back of the cabinet and add a shelf or an extended worktop and a Leg at the far end.
You can make it match the cabinets or contrast. I would contrast it myself.
It would depend on what the issue is. You can strip and paint or refinish the sides. If the top is butcher block, you can scuff with fine steel wool then clean and use a food grade oil.