。
She goes to the library every other day.
Literal
She [topic-は] day [at intervals of-おきに] library [to-に] goes.
~おきに ('at intervals of, every other') is a precise time/distance interval marker — 一日おきに ('every other day'), 一時間おきに ('every hour'), 一メートルおきに ('every meter'). Note the slight ambiguity in modern usage: 一日おきに traditionally means 'with one day in between' (so every 48 hours), though some speakers use it loosely for 'every day.' For unambiguous daily, 毎日 is the standard. Plain present 行く reads as habitual: 'she goes' (regularly, as a routine).