。
She acknowledged that what I said was true.
Literal
She [topic-は] my words [object-を] truth [is-だ-quotative-と] acknowledged.
認める is the verb for acknowledging, admitting, or recognizing — capturing the moment someone concedes a point or accepts a fact. The structure XをYだと認める ('acknowledge X as Y') chains a direct object (を), an embedded predicate (Y + だ), and the quotative と to feed the verb. 真実 ('truth') is a weighty Sino-Japanese noun, more formal than ほんと; pairing it with 認める gives the sentence a deliberate, almost legal-sounding tone — fitting for moments of important concession.