The Google AdWords certification is a professional accreditation that Google offers to individuals who demonstrate proficiency in basic and advanced aspects of AdWords. An AdWords certification allows individuals to demonstrate that Google recognizes them as an online advertising professional.
The format for the exam is 100 questions in 90 mins and you need at least 75% to pass.
The benefits of being an adwords certified individual is that you get a certification badge like this:
And you also get a professional status page hosted on Google which verifies your status which you can link to.