。
I hear she's Mr. Smith's secretary.
Literal
She [topic-は] Smith Mr. [genitive-の] secretary is [hearsay-そうだ].
~そうだ has two distinct grammars that share a written form. Attached to a finished plain-form clause (verb / adjective / noun + だ), it's the hearsay marker — 'I heard that...'. Attached directly to a verb stem or i-adjective stem, it's the appearance marker — 'looks like / seems'. Here it follows the noun 秘書 + だ, locking in the hearsay reading. ~氏 (し) is a written/formal honorific suffix attached to surnames, common in news, legal documents, and business contexts — equivalent to English 'Mr./Ms.' but more bookish than the spoken さん.