How to add UPC codes to product list for barcode generation?

Hello All,

Hope everybody is doing fine.

I have a question on how to add UPC codes to our product list, Like once we get our 12 digit Unique A-UPC. after getting the digits how to add them into our Shopify product list so that barcode can be generated and visible.

And, in terms of Inventory update if we update in Shopify will our other applications or sales channel be updated directly with it.

Thank you very much for your response. have a great day.

Regards