The profession of a Product manager, why and who needs them and what they do?

What does a Product manager do? Which companies need a Product manager and in what situation? How to become a Product manager? 

Who is useful:

Novice specialists in THIS field who want to have an impact on the product, but have no idea where to start and what career opportunities exist in principle in THIS.

The speaker will be Abdugani Sofi (Baidildaev) Director of Products in .