The beep is to let you know that a door is not closed completely or the temperature in the refrigerator or freezer is too warm. Open the doors one at a time and look at the gasket on the door that is still closed. There should be a seal all the way around each door. The gasket should be touching the cabinet all the way around the door.
Check the temperatures and see if they are correct. If the refrigerator has only been running a few hours, it may beep until it gets cold enough.
If the temperatures are good and the doors are closing, you need to schedule service. There may be a problem with the control board in the refrigerator or a door light switch.