Nirvana according to Mahayana Buddhism is the true state of spiritual perfection. It is a state in which compassionate oneness with others has transcended all thought of oneself as a separately distinguishable entity.
Paradoxically put, it means that by renouncing Nirvana for oneself, in love for others, one is already in Nirvana as it is truly understood. Nirvana means the extinction of desire, extinction of hatred and extinction of illusion.