The dialogue is in English and Yiddish, a germanic language that uses the hebrew alphabet.
The vigil referenced in the title is Shemira, a Jewish custom in which a guardian, usually a relative or close friend, spends the night in the same room as the recently deceased before a morning funeral. The guardian spends the night reading the psalms to comfort the dead and to prevent evil spirits from possessing the deceased or the guardian.
In December 2019, Blumhouse acquired domestic distribution rights to the film.