This is a buzzer circuit.It could be used in many circuit just to make it more fancy or maybe as an alarm.What it does is whenever you switch on the switch the buzzer(light bulb as we don't have a buzzer in ec) will beep and automatically stop beeping.It will never beep again until you switch on the switch in future.The output of the first IC 555 could be also used as an input for UM3561 which is a IC which gives musical outputs for buzzers.Wishing you all a happy new year 😀😀
