。
She sometimes takes a walk in the park.
Literal
She [topic-は] sometimes park [object-を] walks.
Notice the surprising を on 公園 — 散歩する ('to take a walk') is one of those motion verbs that takes を to mark the path or area traversed, not the object. Same logic as 道を歩く ('walk along the road'), 川を泳ぐ ('swim across the river'), 空を飛ぶ ('fly through the sky') — for verbs of motion, を marks the space the motion takes place in. This is a learner trap: the を looks like a direct object marker but is functionally a path marker.