Airbag light on with a code 53
P0053 is for an O2 sensor, which should give you a CEL.
Which ever the case you need to take it in.
If that is an airbag code, it means this;
B0053 Deployment Commanded with Loop Malfunctions Present
So the airbag computer thinks you hit something and it is trying to pop the bag. If it succeeds, you’ll have some issues!
If this is an ENGINE code… a P0053… then @Purebred is correct, that’s an O2 sensor problem that has nothing to do with your airbags.
The OP didn’t mention the check engine light, which ought to be on if there were a problem with the O2 sensor. My money’s on the airbag.
After the airbags have been deployed, the airbag control module and the airbags must be replaced. That fault indicates that the control module (Inflatable Restraint Sensing and Diagnostic Module) was not replaced.
That would mean the light was on when the OP bought the car. Apparently it was in an accident that wasn’t disclosed.