The group can be named anything you like and you can also use the group identifier section for your own reference, this could be something like a course code or an accreditation number.
It's important to note that if you have the [Group.course_name] attribute in use on the certificate design that this group is using, then whatever you call the group will automatically be pulled into the certificate design and used in the text box when a certificate is created. As such it's important that you name your group with the appropriate language that you want to see appearing on the certificate.
So here's an example of the group details form filled in:
And here's an example of the above entered course details pulling into the [course_name] placeholder on a completed certificate being issued from this group: