In my iPhone 5there isn't Books in restriction :-( and How can I download Kindle?bought in UAE

Your question is unclear so I'm guessing as to your meaning, but Apple does not at this time offer paid books in the UAE iTunes Store.

As to the Kindle app, if that's available in the UAE iTunes Store, you can download it. If it's not, as it may well not be since Amazon may also not have any book distribution rights in the UAE, then the Kindle app will not be available to you.

Regards.

The Kindle app doesn't appear to be in the UAE store, so I assume that Amazon haven't granted Apple a licence to have it there.

Kobo appear to have their app available there : Kobo. So you might be able to get ebooks from them.

Most ebooks have digital rights management on there which tie them to the store's own apps/ereaders - so if buying from Kobo then you will probably only be able to read them in the Kobo app etc

Settings > iTunes & App Stores > tap your Apple ID: > View Apple ID > Country/Region

If you find that it is set to the correct region, log out of your iTunes Store account, restart your iPhone, and sign into your account again.

Regards.