Depends on what you mean. A hijab has no magical powers. In a muslim society i suppose it protects a woman because its exoected of her and shows she complies with her societal norm, showing muslim men shes being obedient. In a non-muslim society it could actually hold her up to mockery and derision and even put her in more danger because of strong anti-muslim sentiment. If someone were intent on hurting her a hijab would do nothing. Its just a piece of cloth.
Only because she is apparently responsible for the fact that men can't be expected to control themselves. Just as in many places of worship where the men are all in front and the women are on the back. Thankfully some brilliant man came up with the solution of men being expected to keep their minds on worship while they can see a females nearby!
Hijab hides women graces, that could kill men lust. In our country most women wear hijab just because of social restrictions. A small group like it. Some use it for misdirection and do harlotry under it. Hijab isn't a masterpiece for our men. Actually a lot of our men hate it. Also a lot women. My experiences are females with hijab are dirtier than females with no hijab. you can't recognize the sluts with no hijab but I know some of them.
Hmm .. read this entire thread and the conversation metamorphosed from talking about a religious perspective to a all out squabble about who knows what.
People .. calm down!
There are many differences about our religions .. I am Christian, and I can also argue about fact vs fiction when it comes to differences between Christianity and Islam .. But .. that is a conversation I will not partake in. People far more knowledgable than me haven't been able to win that argument .. and never will. We just have to agree to disagree .. out of respect for 'free will' .. although even 'free will' has an entirely different meaning from either perspective...but you know what I mean.
Getting back to the original question .. I can only answer with a question .. "Protect" from who? From God or from men who have no self control?