은 자기가

… oneself; … that they themselves …

→ 은

phrase Rare #32,254

… oneself; … that they themselves … 은 marks the topic, while 자기가 refers to the topic as the subject of the following clause. The exact English wording depends on context.

KO: 톰은 자기가 바쁘다고 메리한테 말할 거야.

EN: Tom will tell Mary that he is busy.

톰은 자기가 바쁘다고 메리 한테 말할 거 야.

Tom will tell Mary that he is busy.