학생

In a sentence

• 그 학생은 항상 열심히 공부해요.

  That student always studies hard.

  Here, '학생' refers to an individual who is currently studying, used as a noun in a subject position.

• 학생들이 교실에서 이야기하고 있어요.

  The students are talking in the classroom.

  '학생들' is the plural form of '학생', indicating multiple students.

• 제가 학생 때는 매일 일기를 썼어요.

  When I was a student, I wrote a diary every day.

  Here, '학생' is used to refer to someone's identity during a past period of life, commonly skillfully combined with time expressions.