It is the postcode of the address in the UK to which your bank statements are sent.
This appears to be one of the security questions HSBC requires when registering to their Verified by Visa system.
Verified by Visa helps protect your card against unauthorised use when you shop online with participating retailers.
When you make a purchase in a store you have to enter a PIN to confirm that the card is yours. Verified by Visa works in the same way but for purchases made over the Internet.
Your monthly bank account statement gives you a detailed review of the activity in your account for a specific period of time. It's your best opportunity to make sure your records match the bank's.
Learn the anatomy of a bank account statement shared by Bankrate.com to learn more.