The project manager's job covers a broad range of roles—leader, facilitator, marketer, problem solver, task master and advocate, to name a few. The main focus of the job also shifts some as the project matures from phase to phase. During Initiation and Planning the PM leads the team in defining the project very explicitly, gathering and consolidating information on what the project is supposed to accomplish, identifying the deliverables needed to do so, and creating a plan for the project to get to the end goal. The PM must communicate the plan to executives and stakeholders for their agreement and support, including the resources the plan calls for.
During execution—as the team does all the work called for in the plan—the manager monitors progress on the plan and most importantly, whether the project is meeting its overall objectives. The PM makes sure issues are addressed as they come up, and lets the project sponsor and all the stakeholders know how things are going. More than monitoring, the project manager also should anticipate—actively looking for new risks, looking for ways to make everyone's work easier, looking for obstacles to remove.
As various deliverables are completed, the PM's job shifts again to drive "end game" activities, which often include significant cross-functional work. Multiple groups in the organization have to work together to finish up the project—reviewing what the project has created, ensuring the requirements previously defined have been met, and preparing to deliver the outputs of the project to its customers.
When the project is almost done, it's the project manager's job to make sure it's truly almost done, then close the project out gracefully. The project manager makes sure that everything is reviewed by the right people and the customers will be happy with the results. They also make sure that the transition to customers will be smooth. What's needed to provide the outputs of the project to its customers and have that go well? Is training needed? Special documentation? Presentations? Ongoing manufacturing setup? Whatever is appropriate for your type of project, there are typically lots of aspects of finishing a project that go beyond just the main content or features of its deliverables to deployment needs. The project manager should make sure those aspects were planned earlier, and makes sure during the end game that it's all coming together. As the project comes to completion, the PM also makes insures team members don't disappear before their end game work is really done. They ask what documentation should be archived for the records, and they lead the team in capturing lessons learned to help future projects.
The role of the Project Manager is discussed in Project Manager/Team Leader Description - Roles & Responsibilities, which lists the core work and critical underlying responsibilities of a project manager or team leader. It goes beyond the standard "planning, tracking, communicating" list of Project Manager job duties, to clarify the mindset and responsibility necessary for success. It also includes thoughts from executives about what they value in their strongest project managers, to help bring the job alive. See also the brief guideline Leadership and the Project Lifecycle for an overview of how the PM's focus shifts during different stages of the project.