I have tried to change ZIP to postcode, but it only says it could only happen in Paython code. But I have changed the English from (US) to (AU), of which it should appear Postcode, but it didnt!
It seems you are trying to update label directly from fields. By default in Odoo when you create any field then it doesn't update directly update from Odoo. You need to update it through Python code only.
But as your requirement is not show label language wise then you achieve this thing via updating placeholder inside views. Please follow below steps,
Go through below path,
Settings -> Technical -> User Interface -> Views
Then search for "view_partner_form" view.
When you will open that view then you will find a clickable label "Edit Translations".
When you click on that label then popup will appear. In popup you can search for "ZIP" label and update translation as per your requirement.
So this is how you can achieve that part.
Feel free to ask in case you have any doubts related to the above points.
Ashish Singh (Team Lead)
Webkul Software Private Limited
THIS HAS WORKED AMAZINGLY 👍🏼
It's great that your issue is resolved. If you liked my assistance then I would really appreciate if you can take out a few minutes out of your busy schedule and put a google review for us here -