What does a project manager do

A successful Project Manager must simultaneously manage the basic elements of a project. No matter what industry you are in, there are really four basic project elements. These elements are:
1) TIME
2) MONEY
3) RESOURCES
4) SCOPE

All these elements are interrelated, and each must be managed together if the project is to be a success.

Resources:
People, equipment, material

Time:
Task durations, dependencies, critical path

Money:
Costs, contingencies, profit

Scope:
Project size, goals, requirements.