As a single sentence, the meaning is:
She deserved it!
But only related to a negative event, so like to say /justice is (at least partially) done/.
Grammatically it is: Bene [questa cosa (implicit subject)] sta a lei.
With a completely different meanig, if you want to say: /this coat suits her/, you would say:
questo cappotto le sta bene.
Notice the inversion og order of {bene, sta} in the two meanings!