。
The bearer of this letter is my friend Mr. Suzuki.
Literal
This letter [genitive-の] bearer [topic-は] friend [genitive-の] Suzuki-[diminutive-くん] [copula-です].
Formal introduction letter phrasing. 本状 ('this letter/document,' with 本 meaning 'this') is formal-register, common in business correspondence. 持参人 ('bearer, the one who brings') is a formal legal/business term for someone carrying a document. The sentence reads like an introduction letter a businessman might carry to a meeting — old-school formal Japanese.