As Heidegger uses it, 'Dasein' is a difficult term to understand and to translate. In ordinary German it means the same as 'existence,' but Heidegger uses it to pick out specifically human existence. Further, it picks this out in a specific way. Heidegger says that 'Dasein' picks out the entities that we are and that it picks us out with regard to our being: "we have chosen to designate this entity as 'Dasein', a term which is purely an expression of its being" (SZ12). So 'Dasein' is a peculiar, ontico-ontological term: it designates an entity but with regard to its being.
Insofar as 'Dasein' refers to the entities that we ourselves are, we might be tempted to mentally substitute for it a term like 'person' or 'human being.' The problem is that, while these words designate the same entity, they pick it out in ways that Heidegger wants to avoid. 'Human being' picks us out with regard to our humanity as opposed to animality or divinity, and 'person' picks us out in terms of our agency, consciousness, and/or personality. While these ways of understanding us do get at genuine features of us, they nonetheless obscure that aspect of us that Heidegger is interested in: our openness to being. Heidegger uses the term 'Dasein' to pick us out as being (Sein) there (da), where by 'there' or 'da' Heidegger means what we might call the space of intelligibility or meaningfulness. Calling us 'Dasein' thus names us as entities who essentially make things intelligible or who dwell in a meaningful world. Dasein is the entity that understands being. The story that we tell about Dasein is thus not a story about agency, consciousness, animality, or divinity, but a story about sense-making.
Pp. 69-70