。
She set out for Osaka yesterday.
Literal
She [topic-は] yesterday Osaka [toward-へ] set-out.
立つ here carries a less-common sense — 'to depart, set off on a journey' — far from its everyday meaning of 'stand up.' That departure meaning is now usually written 発つ, with 立つ as the older, slightly literary alternative; both spellings share the reading たつ. The へ marks Osaka as the direction of motion, distinct from the を used with 発つ to mark the origin (大阪を発つ would be 'depart from Osaka'). A small choice of particle flips the geography between coming and going.