Sales (ventas) remain a vital element for all companies and the international element to this aspect is becoming increasingly important. When I hear Spanish people speak about an individual who works in a sales department they often say: "Who is the commercial?" or "Can I speak to the commercial?"
This is not correct and is an obvious translation from Spanish. The way you need to ask for someone in the sales department is: "Can I speak to a sales representative?" or "sales rep".
The general meaning of "commercial" in English is related to commerce and can be used to mean "advert" especially in the US. It can also be used as an adjective such as: "commercial area" or "commerical district" which describes a zone where commerce takes place.
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 10 años de experiencia enseñando inglés a españoles.