This is a polite phrase used when you didn't catch what someone said and want them to repeat it. "すみません" means "excuse me," and "もう一度" means "once more." "お願いします" means "please." It's very useful in conversations when you need clarification.

何かをもう一度言ってほしい時に使う丁寧な表現です。「すみません」は「ごめんなさい」で、「もう一度」は「もう一回」という意味です。