This is information you you have created an apple id.
To use this apple id for the itunes store, you have to agree to the terms and conditions and enter in the requested information before you can use the store.
When you create an apple id it does not mean you gain access to all apples features, you would need to create a :-
Game centre id
You can use the same email address as each login. but until you agree to each terms and conditions you wont be able to access the services.
This is usually done the first time you access each service and sign in with your apple id.
As to iTunes you need a little extra as they will request to confirm details as to address, etc, with the payment information they can confirm you are actually in that country you are trying to purchase from.
Once you have added the credit card details, you can go back in a set payment method to none and remove the credit card details once you have activated the itunes on your apple id.
Basically this message you are getting is just ADDING the feature of iTunes store to your apple id, and confirms you have not got a iTunes id yet.
As I mentioned each service can be added to your apple id, and each service has its own terms and conditions.
Unless you agree to these you cannot use that sertvice.
As mentioned you can enter credit card details first time, this is basically to prove your address details, so you are purchasing from the correct store, e.g. you cant create a US itunes id and purchase from there if you dont have a billing address in the US.
Once its created you can remove your credit card details by selecting the payment method NONE.
You can create a itunes id without credit card details by using this method.
But if you already have an apple id with your email, then you will not be able to use this method, this is only available on new apple id's