In the same way a CPA validates one's accounting abilities or an MBA speaks to one's business acumen, a Project Management Professional (PMP) certification gives weight and authority to any project manager's CV. This globally-recognized accreditation from the Project Management Institute proves a project manager's ability to navigate all aspects of the job, from workflow management to a key methodology such as Scrum. And in many ways, a certification can set the tone for your resume to recruiters, giving them clarity about your experience.
One resource that can help you study for the certification is the Official PMP 6 Certification Training Course. And right now, you can get full access to it for $79.