a person who studies a lot; a studious, diligent learner (often a compliment).
母は昔からの勉強家で、毎晩英語の勉強を欠かさない。
My mother has always been studious and never misses her English study at night.
彼は本当に勉強家で、試験前は図書館にこもることが多い。
He's truly a studious person and often locks himself in the library before exams.
あの先輩は勉強家だと同級生から尊敬されている。
That senior is respected by classmates for being studious.