scholar; student of learning
A somewhat literary or formal term for a person devoted to academic pursuits; not an everyday word for 'student'.
As a true scholar, he devoted his life to research.
Those who pursue learning should always be humble.
学生 is the standard word for 'student' (especially in an institutional setting). 学問の徒 is not used for ordinary students.
Compound of 学問 (learning, scholarship) + の (possessive particle) + 徒 (follower, adherent). The exact historical derivation is uncertain, but it follows a classical pattern for describing a person devoted to a pursuit.