。
My older sister's hair reaches her shoulders.
Literal
Older-sister [possessive-の] hair [topic-は] shoulders [up to-まで] reaches.
姉 (あね, 'older sister') is distinct from 妹 (いもうと, 'younger sister') — Japanese carries the older/younger distinction baked into sibling vocabulary, unlike English. 届く ('to reach, to extend to') is intransitive — the hair is the subject of its own reaching, with まで marking the destination ('up to the shoulders').