This is the 4569th most frequent Korean word.
가르치는
"Teaching."
The word '가르치는' here means 'teaching', describing the ongoing activity of the subject who teaches the children English.
그는 아이들에게 영어를 가르치는 일을 하고 있습니다.
He is working teaching English to children.
In this sentence, '가르치는' is used as a verbal noun, referring to the general concept or act of teaching.
가르치는 것은 제가 가장 좋아하는 일 중 하나입니다.
Teaching is one of my favorite things to do.
Here, '가르치는' is part of a verbal phrase '가르치는 데', which denotes the act of teaching in the context of using the book effectively.