He really hardly ever complains about his college life.
Literal
Really he [topic-は] own [possessive-の] college-life [target-に] almost complaint say not.
ほとんど~ない ('hardly, almost not') is a near-total negation. 不平を言う ('to complain') — 不平 ('dissatisfaction/complaint') + を言う. 自分の大学生活 ('his own college life') specifies the scope. 本当に emphasizes the speaker's surprise or admiration.