How Can I sales by scan barcode (Android)

Hello,

To make sales using a barcode scanner you need to add barcode to your items and pair a barcode scanner to your POS device.

You can check the list of  supported barcode scanners here.

You can also use the built in camera of the POS device as a barcode scanner.

All details on how to make sales using a barcode scanner can be found in this help article:

How to Sell Items Using Barcode Scanners

Android mobile phone not support barcode with weight scale (sku+weight)?

Scanning barcodes with embedded weight is available only on iOS devices at the moment. 
But, this feature will be added on Android soon. 

I looking forward to you.