Like anywhere, a person's character varies from person to person. Just try to relax and be friendly. Because I'm from the US, I'm not sure what would be a culture-shock to those from other places, but be mindful that you're experiencing a different culture. Many things may be different, but if something is offensive or confusing, I'm sure you can ask someone in your host family if it is normal. Maybe you can speak with other Koreans who have visited Kentucky? If there's an exchange program there, it's likely there are other Koreans in Kentucky, too.
I don't know a lot about Kentucky, but I think you're likely to learn a bit about horse racing. Good luck!