The interviewer would like to uncover your experience with identifying, advertising to, and creating a following of potential customers.
You need to explain how you determine what kind of people would be interested in your clients' product or services, and why. Your answer should explain how you research information including demographics, location, educational or professional backgrounds, their challenges, and their goals. When it comes to targeting, you'll need to explain how you know where your customer avatar shops, the platforms they use most frequently, and how they make purchases.
Do not refer to customer profiles or targeting strategies you've implemented using data that came from third-party research. The interviewer wants to know how you conduct research and planning on your own.