To answer your question as clarified in a comment:
All I wanted to know what will happen if I enter my debit card number in the sixteen digit account number they offer on the application for balance transfer. That's all.
Almost certainly (subject to the particular terms and conditions of the offer), no money will move, the only question is exactly when and how they will say no.
If you do it online, and their system is clever enough to look up the IIN (the first six digits) of the card number you enter, their system might learn straight away that you have entered a debit card number (eg a card starting 431940 is a Bank of Ireland debit card).
Otherwise, you'll have to wait until the request goes to their back office system, which will eventually lead to the card issuer's system being contacted, at which point it will become clear that it's a debit card, and your transfer request will be refused at that point.
That said, some credit card companies do offer a "Money Transfer" aka "Super Balance Transfer", which is an offer to transfer money directly into a bank account, putting the resulting debt on the credit card. I've never seen these offered without having to call a service centre and talk to a person, though, presumably so that they can check that the details they have for you (about income etc) are still correct.