She put all the medicine out of the children's reach.
Literal
She [topic-は] medicine [object-を] all children [possessive-の] hand [possessive-の] reach [subject-が] not-reach place [to-に] placed.
子供の手の届かない所 ('a place children's hands can't reach') is a relative clause modifying 所. 届く (とどく, 'to reach') in negative form creates the safety description. A practical parenting sentence.