Catriona Hanley explains transcendence.
Transcendence is freedom; this (finite) freedom is the origin of grounds. It permits the possibility of asking about grounds in the first place, and, as the experience of the identity of being and the nothing, of understanding and finitude, it is the origin of the question of "why." It is Dasein’s understanding of being that makes the why possible, freedom as finite transcendence that is the ground of grounds. Freedom, however, is itself groundless; there is no other recourse than Dasein existing as possibility to be other. Thus freedom is limited, or finite, since Dasein is in a sense determined to be free by its factical existence as thrown. Dasein is factically and therefore finitely free. As such, it is presented with possibilities from amongst which it must choose. In other words, “in transcendence, the essence of the finitude of Dasein discloses itself as freedom for grounds” (WG: 130/131). There is no ground for truth any more than there is a ground for Dasein as free transcendence; there is no statable reason why either should be. Yet Dasein must always and does always presuppose truth in its disclosive encounters with beings in the world. There are beings, available for disclosure; and there is Dasein, as disciosive. The interrelation between the two, here named transcendence, otherwise named Ereignis, is the temporally conditioned understanding that is the essence or ground of Dasein, and is the “und” of Sein und Zeit.