It means. A(fter)/S(ervice) for customers. If you buy computer, TV and so on, you can receive service. Like fixing services.

It means "to provide after-sales service". The term "A/S" is used in Korea instead of "after-sales service" even though it's a broken English.:) \^o^/

I don't know what's that mean but it's colloquial expression and not common thing. I don't know what's A/S stands for but it means customer service. And customer service means provision of service to customers before, during and after a purchase. A/S is often used when people buying car or computer.