Formula to extract number of sold items

Hello all,

I have a huge amount of sales data (sample in the attachment). Currently, I fill column A (= sold amount of 'No. 503 Ginger Delight BIO - 1 kg') manually. Obviously this takes me a lot of time
So I am looking for a way to automatically extract the sold amount for a specific product. In this case 'No. 503 Ginger Delight BIO - 1 kg'.

So the request for help is: how can I automatically fill column A for each row?

I hope somebody can help me.

Thanks a lot!

Kind regards,

Kelly