Behind every successful brand, there is a team of excellent customer service which helps the customers with all their might. Your answer to this question will allow them to assess your industry knowledge. Hence, deciding your job role. Tell them your personal experience about how you bought a product from an XYZ brand because their customer service was at par. Also, if the customer service is great, the customer might come back again and purchase the service from you. Thus, giving you business. This also increases the chance of word-of-mouth advertisement, where the customer will talk about your brand to others who will visit your website or business address and purchase the service. This cycle will continue if good customer service is consistently put in the effort and ultimately adds value to the brand.