The OR Bit is a logic gate with two inputs. Just like its name, if input one OR input two is receiving an ON signal, then it sends an ON signal from its output.
Real World Example
Picture a house that has a doorbell at the front door and a doorbell at the back door. Both doorbells are connected to the same buzzer inside the house. This buzzer will ring when EITHER OR BOTH of the doorbells are pressed.