A beginner student can refer to any of several types of student in the context of EFL and ESL. A "true beginner" is a person who has never studied English before, whereas a "false beginner" is a student who has started learning English in the past and, for whatever reasons, has had to postpone learning.
As Peter Viney points out in an article on teaching adult beginners, "most beginners are false beginners," and in the case of adults, "bring entrenched learning styles into the classroom. Entrenched styles can be changed, but this requires work on learner skills and styles."
Nowadays "beginners" are classified as A1 or A2 on the Common European Framework of Reference for Languages.