She is too short to reach the top shelf.

Literal

She [topic-は] height [subject-が] [too-low-低すぎて], top shelf [contrast-には] hand [subject-が] doesn't-reach.

手が届く is a set idiom: 'one's hand reaches' = 'be within reach.' Negated 手が届かない is 'out of reach,' both literally and metaphorically (out of one's means). The contrastive には emphasizes 'as for the top shelf — [her hand doesn't reach there].'