The INTD0833 is an electronic device which can charge a battery when AC mains line is alive and switch to emergency LED lighting when AC line goes off.
During normal operation, thus the mains 230V AC voltage is present at terminals L and N, the device is constantly charging/conditioning the battery connected to terminal B+ and B-. Notice that the type of battery connected to these terminals should be an SLA 12V/3.2Ah type.
During an 230V AC mains failure, thus the mains voltage is not present at terminals L and N, the device switches to battery backup and powers a 12V LED light connected to terminals LD+ and LD-.