A product manager plans, develops, launches, and manages a product or service. From ideation to development to market entry, it covers the entire lifecycle of a product. 

During all stages of the product lifecycle, product managers ensure that a product meets the needs of its target market and contributes to the business strategy.

Product manager interviews can often be thorough and consist of a wide range of technical and behavioral questions. Some of the domains on which you might be asked questions are product marketing, product lifecycle, sales funnels, etc.