。
She made a man of him.
Literal
She [topic-は] him [object-を] full-fledged [genitive-の] man [into-に] made.
The Xを Yにする pattern ('make X into Y') with 一人前の男 ('a fully-fledged man, a real man') as the resulting state. 一人前 (literally 'one-person-front') is a common idiom for 'full-fledged adult, mature, fully qualified' — applied to people who have grown into a role, profession, or stage of life. Combined with 男 ('man') it produces an idiom roughly equivalent to English 'make a man of him' — implying she shaped him into adult masculinity through her influence.