The PMBOK Guide's sixth edition introduces significant changes, including the renaming of knowledge areas and the addition of new processes to enhance project management practices. It emphasizes a shift from control to monitoring, incorporates agile methodologies, and updates the role of project managers to reflect current trends and demands. These changes will impact the PMP exam, with new content likely accounting for 5-10% of the test material, and PMI plans to launch the updated PMP exam by early 2018.