男生

Chinese often sticks a gender label directly onto the noun, giving you 男学生 or the shorter everyday 男生. The 的 makes 男的 mean the male one, so it stops working as a simple gender label. So 男的学生 sounds like the male one's student, which is not how people say male student. If you want a male student, use 男生 or the slightly more formal 男学生.

男生 and 女生 are the normal pair for boys, young people, and students. 男人 and 女人 mean adult men and women, so they sound older and more grown-up. A university class has 男生 and 女生, while a company party has 男人 and 女人. If you mix them, 男生和女人 sounds like a boy and an adult woman. “女士和男士， 男生和女生， 先生和学生。” (Ladies and gentlemen, boys and girls, Mr. and student.) ── [《医生问问题》](/read/doctor-asks-questions#s1)

男生 literally looks like male student, and in school it usually means exactly that. But outside class, people use 男生 for any young male, even if he is not enrolled anywhere. A woman might say 那个男生挺帅的 about a guy at a bar or gym. If you mean a grown man, use 男人; if you mean a male child, 男孩 also works.