Every applicant gets a Relevance rating. It shows how closely their resume matches the job you posted. It's automatic, so there's nothing to set up.
You'll see one of three ratings in the applicant list and on each applicant's profile:
Match: a strong fit for the role.
Limited Match: some overlap with what you're looking for.
Not a Match: little overlap with the job.
To see your best applicants first, sort the list by Relevance. When you have a lot of applicants, filter by rating to see only the Matches.
The rating is a starting point to speed up your first pass. The hiring decision is always yours.
An applicant has no rating yet if their resume is still being processed, or if they didn't include one.