Counterman (noun)

1. A man who works behind a counter, especially in a shop, bar, or restaurant.
2. A man who works at a counter in a shop or other retail establishment and serves customers.

Origin:

Late 19th century: from counter + man.

Examples:

1. The counterman at the deli was slicing the meat for the customer's sandwich.
2. The counterman took the customer's order and prepared the coffee.
3. The counterman at the gas station helped the customer fill up the car with gas.
4. The counterman at the store was assisting the customer with their purchase.
5. The counterman at the bar served the customer their drink.