。
She really loves his wild performances on the big stage.
Literal
She [topic-は] big [genitive-な] stage [at-で][genitive-の] his wild [genitive-な] performance [subject-が] very is-liked.
Note the unusual stacking 大きな舞台での — で (location) + の (genitive) lets a で-marked phrase modify a noun. The standard pattern for 'X が Y at location Z' becomes 'Z での Y' when packaged into a noun phrase, with の attaching the locative phrase to its head noun (here 演奏 'performance'). ワイルドな ('wild') treats the English loanword ワイルド as a な-adjective — a productive pattern for English-derived adjectives in Japanese.