My airbag light is on in my 02 camry what does that mean on 2002 Toyota Camry

It came on right after we put another transmission in

1 answer 1 comment
Possible damaged wiring to air bag system, left side of vehicle. Check fuses. Can be scan tested!
Is this an expensive repair? What should I say to the mechanic? the light just came on today as I was preparing to take the car for inspection.