You're talking with your husband about his job. You think that he should ask his boss for a raise. He doesn't think his boss will give him a raise, so he's hesitant. To persuade him, you say this.
It doesn't hurt to ask.
This is a well-known set phrase in English. Use it when you think that someone should ask for something, even if the answer is probably "no". Here is another example:
I doubt that he knows where it is, but it doesn't hurt to ask.
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