A formal or literary/archaic adverb meaning 'often' or 'again and again'; in modern usage 'たびたび' is more common.
度々のお運び、誠に有難うございます。
Thank you very much for coming (visiting) repeatedly.
彼は度々旅に出て、新しい土地を見た。
He went on journeys repeatedly and saw new lands.
度々のご連絡、恐縮ですが、ご確認ください。
Sorry to contact you repeatedly, but please check (this).