大学生(dà xué shēng) - university student in Mandarin

大学生 (dàxuéshēng) is a university student. It is simply 大学 (dàxué), "university" (literally "big school"), plus 生 (shēng), the same "student" suffix found in 学生 (xuésheng), "student", and 中学生 (zhōngxuéshēng), "secondary school student".

Chinese neatly grades a learner's stage this way: 小学生 (xiǎoxuéshēng) for primary, 中学生 (zhōngxuéshēng) for secondary, and 大学生 (dàxuéshēng) for university, so once you know the pattern the vocabulary practically builds itself.

一个大学生 (yí gè dàxuéshēng) is "one university student"; for a group, 大学生们 (dàxuéshēngmen) or just 大学生 (dàxuéshēng) used generically both work, since Chinese nouns don't obligatorily mark plural.