가 그러는데

says that; I hear that

→ 가
phrase Common #3,623
says that; I hear that Used after a subject to introduce what someone says or has said, often as background to what follows. The subject particle 가 attaches to the person being quoted.
KO: 엄마가 그러는데, 내일 비가 온대.
EN: Mom says it’s going to rain tomorrow.

의사가 그러는데 아픈 게 정상 이래

The doctor says it's normal for it to hurt.

— 아모레스 페로스 (2000)

수의사가 그러는데 그래서 늘 피곤한 거 래요

The vet says that’s why they’re always tired.

— 시네마 천국 (1988)