。
She didn't show up until the meeting was over.
Literal
She [topic-は] that meeting [subject-が] ends [until-まで] did-not-appear.
~まで paired with a negative predicate ('didn't show up *until* X') flips its usual 'up to' meaning into 'not before then'. Note that the が inside the まで-clause marks 会合 as the subject of the subordinate verb 終わる — Japanese routinely uses が rather than は inside relative or subordinate clauses, since は (topic) is reserved for the main clause. 現れる ('to appear, show up') is the everyday verb for someone or something coming into view; with a person as subject and a negative, it carries a slight nuance of 'failed to materialize when expected'.