。
She's believed to be a genius.
Literal
She [topic-は] genius is [quotative-と] is-believed.
信じられている is the passive progressive of 信じる ('to believe') — literally 'is being believed.' This impersonal passive construction expresses what people in general believe, without specifying who. ~と信じられている = 'it is believed that ~' is common in academic and journalistic writing.