People who come from the southern part of a place, especially the southern part of the United States.
It's just a way to talk about where people come from, not good or bad.
Examples:
The southrons like to eat spicy food.
The southrons have a different accent.
I met a group of southrons on vacation.
The southrons are good at making barbecue.
The southrons always wear cowboy hats.
The southrons are very friendly.