The 4 in 1 Multifuncational EMV Credit Card Reader Writer is a small device that can insert MMC, SD, MS, and SM cards. These cards are used for data storage of some digital devices such as cameras, camcorders, and telephones. With a card reader, you can read it out, that's what it's for.
Insert the desired card into the card reader, and then insert the card reader into the computer's USB port. The computer can read the data on these cards.