This phrase is usually used as a disclaimer before asking a question that the person believes may be obvious or silly. It is a way to acknowledge that the question may not be the most intelligent, but they still want an answer.
Some people may feel self-conscious or embarrassed about asking a question that they believe is obvious or silly. They may apologize as a way to acknowledge their own perceived lack of knowledge or intelligence.
No, all questions have value and can lead to learning and understanding. What may seem like a dumb question to one person may not be obvious to another. Asking questions is an important part of the scientific process.
It is important to be patient and understanding when someone asks a question, regardless of how they preface it. Answer the question respectfully and without judgement. Remember that everyone has different levels of knowledge and understanding.
Remember that asking questions is a sign of curiosity and a desire to learn. It is important to embrace this curiosity and not be afraid to ask for clarification or more information. Also, remember that there is no such thing as a dumb question and that asking questions is a crucial part of the scientific process.