。
Mr. Suzuki has three daughters.
Literal
Suzuki-Mr. [in-には] daughters [subject-が] 3-people exist.
The 'have/possess' structure [X]には[Y]がある/いる literally 'in X, Y exists.' With people, いる is used. 3人 is the counter for people (~人, read にん except for 一人 ひとり / 二人 ふたり). Spoken Japanese commonly moves the counter after the noun and uses it adverbially without a particle — very standard phrasing.