How to market the product?

When we asked to market a product in an interview, we should divided and conquer this problem in the following way:

that depends on what phrase this product is in:
if it is a brand new product
if it is a developing product
if it is a developed product

whether the phrase this product is in, we should always define what our targeted customers are.
then since there might be other competitors too, so we need to perform competitor research.(Knowing about your competitors will help you to communicate with your target audience, distinguish your business from competitors, improve your processes, and navigate challenges in your market. Determine their main advantages and try to improve on them.)
Reach your audience with social networks: by encouraging sharing between friends, but ads from social media.
Regularly measure your app KPIs:

Other ways to market a product or service:
online: Google my business promotions, email marketing, blog posts, upgrade/trade-ins
offline: contest and giveaways