An interesting grammar point, used to state the primary reason for an action in the following clause, while also indicating there are other reasons.
시간이 없고 해서 못 가요.
I don’t have time (amongst other reasons), so I can’t go.
한국 남자친구가 있고 해서 한국어를 배워요.
Amongst other reasons, I have a Korean boyfriend, so I’m learning Korean.
몸에 안 좋고 해서 담배를 끊었어요.
For one thing, it’s bad for the body, so I quit smoking.