You may already know about 5W & 2H. This refers to the questions What, Why, When, How, Where, Who, and How Much, listed in a poem by Rudyard Kipling. In professional project management the first question you need to ask is "Why?"
Every project exists to solve a problem, answer a question, or seize an opportunity. This is the Project Objective. As Project Manager you need to have a clear understanding of "Why does this project exist?" This clear understanding of "Why" will inform your decision making throughout the life of your project.
You may be handed a project in mid-stream or just given a set of targets to deliver. Even so, your clear understanding of "Why" will ensure your decisions and recommendations are pointed in the right direction.
It takes some practice to not confuse "Why" with "What". Too often we want to jump ahead. Just to illustrate, suppose your project involves road building. The reason "Why" might be:
*to ease traffic congestion,
*to provide community access,
*to improve public transportation.
Whereas "What" might be:
*a gravel 2 lane road
*an asphalt 4 lane road with sidewalks.
Don't know "Why" for your project? The reason why your project exists should be contained in your project justification, project business case, project charter, or other documents. Failing that, ask the person who assigned the project to you. If you still can't find it, then write it for yourself, using everything you can find out about why this project exists. Sign it. Then show it to your sponsor or manager as your understanding of why your project exists. Ask them to sign it too. This will be a great reference for everyone involved in your project!