What transactions are considered as giro for the uob one account?

Rather than what transactions are considered GIRO, it should how the transactions are made. GIRO is an arrangement with your bank to make payments directly to a billing organisation (BO) for any outstanding bills.

You can check your bank statement to check the type of transfer between banks. It could be utility bill, telco, or others, as long as the mode of payment is by GIRO.