했어요= said 저는 태형이 커피를 안마신다고 햇어요 i said i don't drink 태형's coffee

안녕하세요? verb + 는/ㄴ다고 하다' is used to quote what someone said. '-는다고 하다' is used with verb stems ending in a consonant and '-ㄴ다고 하다' is used with verb stem ending a a vowel. So '저는 태형이 커피를 안 마신다고 했어요' means 'I said that 태형 doesn't drink coffee.

it is not correct sentence anyway. so I can't understand what this sentence means but I guess 태형이가 커피를 안 마신다고 했어요. 했어요(하다) means in this sentence, "someone told me (or said) that~" 태형이가 Taehyeong 했어요 said that (told me that) 커피를 안 마신다고 he didn't want to have a cuppa. 했어요 in this sentence, '말' is omitted. 말했어요 >> 했어요. we omitted like that very often. :)