This "thing" is for generating barcodes, both GTIN13 (known as EAN13 or UPC-A) and Han Xin Code.
You can input your message, or you can shake your iPhone/iPod. Both work well to get your barcode!
Make sure test them using your barcode scanner, barcode reader, etc. If the result match the message you input, great, you get a good barcode device. If not, sadly, close this app > phone the producer of the device > tell them: "They got problems !!!".
Now, HAVE FUN ~~~ ^_^