Why is my airbag light on?

There is a switch in your seat buckle that tells the engine computer your seat belt is buckled, thus enabling the airbag. If that switch or the wiring going to it are damaged or fail, you would get the kind of reaction you're seeing.

Your best course of action would be to have the computer scanned to find out exactly what issue is causing those lights. Unfortunately a standard OBD-II scanner won't do the job; seat belt and airbag systems require more sophisticated machines so you'll need to contact a dealer or independent mechanic and pay them to scan the codes. Once you have that information, you'll have a much better idea of where to start with fixing the problem.

I'd start with inspecting any wiring going to the seat belt buckles and the seats themselves; there is often a sensor on the passenger seat to tell when someone is sitting there for enabling or disabling the passenger airbag, so you'll want to check the wires to that as well.

It's hard to be precise with these answers since you haven't told us what year your Kia is, so if you can add that information to your question we may be able to get more specific with our responses. If there is relevant submodel info we should know, please add that too.