Why my S3 device sounds when magnetic card is put on its back?
Your S3 has an NFC chip in it that can read and write NFC tags which are a type of RFID. RFID is most commonly used for things like identification chips for dogs and NFC for public transport payment cards like Octopus or Oyster. It's also in quite a lot of credit and debit cards now too.

The card will have some kind of tag in it - the NXP TagInfo app will give you information about what kind of tag it is.