This is the 2903rd most frequent Japanese word.
もう一度
"もう一度" means "one more time" or "once again."
In this sentence, 'もう一度' means 'once more' or 'again', and is used to ask for repetition of an action, in this case, asking a question again.
「もう一度、質問をしてもいいですか？」
"May I ask the question again?"
Here, 'もう一度' is used to politely request the repetition of an action—performing the song one more time.
「もう一度、歌ってください。」
"Please sing that once more."
In this example, 'もう一度' indicates performing an action again, stressing carefulness or thoroughness in checking a document.