한국어로 이해하나 색해서요 I think what your friend actually said was 한국어로 이해하나 어색해서요 It means that even though i can understand in Korean, it sounds a bit awkward. In addition, the similar grammar to your question could be 하지만,다만 For exmaple, 한국어로는 이해"하지만" 어색해요. Another example, 한국어로는 이해한다만 어색해서요 I hope my answer is helpful for you :)

이상하네요.저 문장은 한국친구에게 받았는데요.ㅋ 그 친구 ㅋㅋ 감사합니다.^^

한국어로 이해하나 색해서요 ?? i think it's a mistake. I cann't understand though i'm native