rescue email address:g•••••@hotmal.com i wont to correct hotmail.com

If you know the answers to your security questions then from http://support.apple.com/kb/HT5312 :

1. Navigate to appleid.apple.com using your web browser.
2. Click "Manage your account"
3. When prompted, sign in using your Apple ID and password.
4. Click Password & Security
5. You'll be asked to answer 2 of your 3 security questions before you can make any modifications. If you are unable to remember your answers, you can choose to send an email to your rescue email to reset your security questions.
6. After you've validated your identity by correctly answering your security questions, click Editto the right of your rescue email address.
7. Once you've finished editing your rescue email address, click the Savebutton directly below the email field.

If you can't remember their answers then you will need to contact iTunes Support / Apple to get the questions reset.

Contacting Apple about account security : http://support.apple.com/kb/HT5699

When they've been reset you can then use the above steps to update your rescue email address for potential future use.

is it for iPad or Iphone ?

I have an iphone 4 showing that at the activation screen.

Type in the id of the account that was being used in Settings > iCloud on the phone, and its password.

If you can't remember the account's password : http://iforgot.apple.com

i bought the phone but it seems the previous user didn't erase it from their account.

You will have to contact the previous owner, only he /she can remove the phone from their account (Apple won't be able to do it for you) : Turn off Find My iPhone Activation Lock - Apple Support

i have no contact details of the previous owner.

If you don't have their contact details then you won't be able to reactivate and use the phone