This is the 6756th most frequent Korean word.
이론을
The Korean word "이론을" translates to "theory" (accusative form) in English.
Here, '이론을' refers to the direct object 'theory' being studied.
이론을 공부하는 것은 중요한 기초입니다.
Studying theory is an important foundation.
In this sentence, '이론을' denotes the theory that is being proposed.
그는 새로운 이론을 제안했다.
He proposed a new theory.
'이론을' is used here to indicate the theory that is understood.