What does fixin mean in the south?

I'm curious, what exactly does the term "fixin'" mean when used in the context of the southern United States? Is it a colloquialism specific to the region, or does it have a broader meaning? How would you use it in a sentence? Is it more commonly used in certain types of conversations or social settings? Understanding the nuances of regional language is always fascinating, and I'd love to learn more about this particular phrase.