I see your profile lists you as in the Philippines, in which case I don't know what suppliers you have locally.
The diode is a 13V (clamp voltage), 600W peak power device, the idea being it clamps fast pulses etc present on the incoming 12V power line. Other names for these devices are Transil & TransZorb I believe.
If you can point me in the direction of a web-site for a supplier local to you I can take a look & suggest an alternative. In the UK we use, RS Components, Farnell (Newark in the USA), Digikey etc etc, but I'm not sure if they have a presence in the Philippines.
Regards,
MrB.