First of all, the words sign and symptom have different meanings in medicine. A sign is something that a physician can directly observe, verify, or measure, like acne or hirsutism which is visible to the naked eye. A symptom is something that a patient reports, but which a physician cannot directly observe, like mood swings or pain. Also, not all women with PCOS will have the same collection of signs and symptoms or the same severity for each. Every woman is different and every instance of PCOS is different.
What is PCOS? That is a very good question, and you'd get very different answers depending on whom you asked.