question about lunch and dinner in specialty resturants on vision of seas

we have voucher/credit from travel agent for 1 free dinner in special restaurant and also one lunch. Is there anything we need to know ahead about using these perks .....are we restricted in anyway or do we just make reservations as if we were paying......the travel information does not indicate which restaurant ....any cautionary tips

The details should come from your travel agent. Many times there are conditions on the use of the voucher. Typical would be the requirement to book on board.

Sometimes you can only go on a port day. Best to check with your TA.