What does a product manager actually do?

Responsible for nothing ... Accountable for everything

You know when we prepare curry, there's always that taste, the taste we don't find in any other cuisine. Some say it's heeng, but we all know it's the cumin seeds. Product manager is the guy who always throws jira into the product curry. Designers might decorate it with coriander, bay leaves or some shit, developers might slow or pressure cook it, but it'll be missing that taste without the product manager.

someone please answer this properly

You are a good question

Pretend that without them the whole project will fall apart.

They pretend to do something and do nothing. Not worth knowing what they do.

To put it in a non abstract way, it is having a product vision (some idea of where the product needs to go couple of years down the line), understanding what all things need to be validated & built inorder to move in that direction & then aligning all functions towards that. The no 1 skill required for a PM in my opinion is Cross Functional Stakeholder Management. And by CF I don't mean Engineers or QAs or Analysts. Its people who will not have any idea what you are working on and will not care to do so on many occasions. Like Marketing, Sales, Finance, Ops, CS etc. They are from a different universe. It all comes down to how you direct a product when 100 different things are pulling you from 100 different directions. I get where the 'PM doesn't have any value addition' thought comes from, but outside of an early stage pure tech product sold to a pure tech buyer, nothing works in silos in a business. And PM is the name given to the bridge between silos as of now.