This is basically what you need to do 'to do' the work In simpler terms, when you are out to create a software you will have to gather requirements and complete a system requirements document. This will be followed by a high level design document, coding, testing and delivery. But at the same time for a construction project, right after the requirements are signed off, you will move on to create a CAD drawing. Consider creating a software but working on partial requirements followed by coding, testing and delivering them. And then in the next iteration again delivering some more requirements. This is also a project life cycle which is following the Agile methodology. The point is, there are different types of Project Management/Project Life Cycles but all of them essentially deal with the activities that are required to be done in order to deliver the project. These activities may have different names and characteristics depending upon the type of Life Cycle in practice Project Management Process
This is basically what you need to do 'to manage' the work All projects, no matter what industry and no matter what Life Cycle they follow, will always have the five project management processes viz. 1. Initiation 2. Planning 3. Executing 4. Monitoring and Controlling 5. Closing However, an important point to note here is that each phase/activity of project life cycle may involve all project management processes. For instance, collecting requirements itself could be initiated, well planned and executed! And ofcourse it would be monitored and controlled throughout before the final sign off and closure.