On mobile devices, the camera is used as a barcode reader scanner. You may active this option at Settings > Products > Products > Use Barcode Reader > ON
When creating a sale or a new product you will see the scanner icon on the top right site of the screen
When you press the scanner, you may see some icons on the bottom. Press the gear icon to activate the codes available then Done.
Additionally, on the products screen from the Gear icon, the option Scanner Entry allows set how many units will be added to the basket when scanning barcodes, by default is set to 1