Prajñā (Sanskrit) or paññā (Pāli) "wisdom" is insight in the true nature of reality, namely primarily anicca (impermanence), dukkha (dissatisfaction or suffering), anattā (non-self) and śūnyatā (emptiness).
In Mahayana Buddhism, the importance of prajna was stressed in combination with karuna, compassion. It took a central place in the Prajñā-pāramitā Sutras, such as the Heart Sutra. Prajna is spoken of as the principal means of attaining nirvāna, through its revelation of the true nature of all things as emptiness.
^Richard Gombrich (2006). Theravada Buddhism. Routledge. p. 47. ISBN978-1-134-90352-8., Quote: "All phenomenal existence [in Buddhism] is said to have three interlocking characteristics: impermanence, suffering and lack of soul or essence."