I think I have a pretty good idea of what they mean. In the div element that loads the profile, they want an additional class with the name of the profile type. Here's a screen shot showing this ("default-users" is highlighted):
By having it in the first loaded div element, this gives the user full control of styling based on the profile type. So if a user type was named "Premium Users", the class that would load in would be "premium-users". This would allow us to hide elements based on profile type, hence adding another layer of flexibility. Classes can go a long ways.