A certificate is a document issued upon the completion of a training program. It signifies that you have trained on specific skills, have trained with a particular individual, or have acquired knowledge in a particular subject.
Certification, on the other hand, often requires you to meet specific standards, pass rigorous exams, and many even include additional practice, consultation, supervision, evaluations, and ongoing continuing education requirements. While you will need to pass an exam, this course does not include many of these elements — making this a "certificate" program.
So while there are a lot of "certifications" out there — including some that are not endorsed by an actual certifying body or even taught by a licensed trainer — you need to be the judge of what adds value to your work and your ability to help your clients.
This certificate does distinguish you as a professional who has trained more extensively in Polyvagal theory with Rebecca Kase, and it's an acknowledgment that can set you apart in the eyes of clients and peers.