The use of the second person plural y'all is associated with Southern American English, but is also used by those who have moved to other parts of the U.S., their family members, and some speakers of African American English. We would call this type of feature:

Question

Quizplus · Accepted Answer

The use of "y'all" is group preferential because it is associated with certain groups but not exclusive to them, as it can be adopted by others outside the original group.

The Use of the Second Person Plural Y'all Is Associated