。
She is widely known.
Literal
She [topic-は] widely is-known.
知られている is the passive of 知る ('to know') in resulting-state ~ている — 'is in a state of being known.' Combined with the adverbial 広く ('widely'), it states fame in a general, ungrounded way. Compare 有名だ ('famous') and 知られている: the latter is more diffuse, suggesting recognition has spread, while 有名 makes the celebrity status explicit. 広く is the く-form of 広い ('wide, broad').