AppStore

iTunes [Store] Support - Use this form for assistance with account and billing, code redemption, or purchase questions - https://ssl.apple.com/emea/support/itunes/contact.html

I agree, the message is confusing. Many have posted similar questions and I suggest you send feedback to Apple about it . There is als no mention in any support documents what "verification" actually means. - http://www.apple.com/feedback/itunesapp.html

Use the first link in Limnos's post or contact iTunes Support. Scroll to the bottom of the page in the 2nd link.

iTunes Support – world wide

What happens if you tap Okay? The request is for you to verify your billing information.