。
She sings better than anyone else in the class.
Literal
She [topic-は] class [of-の] anyone [than-よりも] singing [subject-が] is-good.
誰よりも ('more than anyone') is a universal comparison built from 誰 ('who/anyone') + よりも (the comparative より with emphatic も). Combined with a positive predicate, the wh-word + よりも pattern asserts the speaker's claim is true against the entire reference group — 'better than anyone, more X than anyone.' This is the productive template for absolute superlative claims using comparison rather than 一番. Same structure as 何よりも ('more than anything'), いつよりも ('more than ever').