The word literally means “blowing out” — as one blows out a candle. What is extinguished is not the person but the three unskillful roots: craving, aversion, and the delusion of a separate self.
Nirvana is not a place one goes to after death. It is available here, in this life, as the radical ease of living without the three fires. Mahayana Buddhism insists more strongly on this: “Samsara and nirvana are not two,” said Nagarjuna — whatever is true of one is true of the other, once Emptiness is seen clearly.