An idiom meaning 'to be second to none' or 'to be unmatched' — someone or something is unsurpassed in ability or quality.
彼の包丁さばきは右に出るものはない。料理人として一流だ。
His knife skills are second to none. He's a top-class chef.
あの会社の製品は品質が高く、右に出るものはないと評判だ。
That company's products are reputed to be of such high quality that they are second to none.
彼女の知識の深さは右に出る者はいないと言っても過言ではない。
It's not an exaggeration to say that no one surpasses her depth of knowledge.