。
She didn't go far.
Literal
She [topic-は] far [as far as-まで] did-not-go.
遠く is the noun-like form of the い-adjective 遠い ('far'), here meaning 'a distant place / a long way.' Most い-adjectives can convert to a noun-like adverb by replacing ~い with ~く (近く, 早く, 多く), and many of these forms double as full nouns. The particle まで marks the extent or upper limit reached: 'as far as that distant point.' Combined with the negative, the whole sentence delineates how far she didn't get: she went, but only so far.