"That boy was short in twenty seventeen."
Translation:저 남자아이는 이천십칠 년도에 키가 작았습니다.
My impression is
이천십칠 년도에 그 남자아이는 키가 작았습니다 = In twenty seventeen, the boy was short.
(1) Emphasis is put on the year
(2) 그 [Noun] = The [Noun]
그 남자아이 = The boy (~ he/him, referring to some boy either present within arm length of both interlocutors or not in sight but known to both interlocutors).