"Teachers like teaching."
Translation:선생님들이 가르치는 것을 좋아해.
것 here is a noun, and means "thing."
이/가 is a subject marker, 을/를 is an object marker, and 은/는 is a topic marker
So, because the teacher is doing the action, we put the subject marker on teacher. Since the 것 is receiving the action, we put the object marker on it.
The literal translation is:
Teachers like the thing that teaches.
But, in English, this "something that" grammar can be converted into an "-ing" noun. For instance:
가르치는 것, the thing that teaches OR teaching
수영하는 것, the thing that swims OR swimming
적는 것, the thing that writes OR writing