The gerund (verbal noun) of ná- “to be” (PE17/68), so “being” as in “the state of being” rather than “a living being”.
Quenya
ëasta
noun. existence, being
návë
being
návë
noun. being
ëala
being, spirit
ëala noun "being, spirit" (pl. ëalar is attested), spirits whose natural state it is to exist without a physical body, like Balrogs (MR:165). The word apparently originates from the participle of ëa, q.v.
návë "being", *"to be", infinitive (or gerund) of ná; see ná #1. (PE17:68)