There are a lot of things that are connected to the SRS system that can cause the airbag light to turn on. After an accident the most common things are: airbags, seatbelts, anchor pretensioners, buckle pretensioners, sensors, and more.
If the vehicle wasn’t in an accident and you have an airbag light, these are somethings that could cause that: bad fuse, electrical connection, harness open or shorted, and many other things.
To find out what is causing the light to go off, you must get the vehicle scanned.