Thank you for your quick answer. I understand what you are linking to. But the problem is that I don't have a way to export custom labels and description fields. How to export a PO file for the label and description custom field Metabox? Can you give me the script or tutorial? We need to create a new PO file from the values stored in the label and description Metabox.
Thank you for your reply. Can you please tell us about how to most easily to get a PO File containing all labels and descriptions of the custom fields? Because putting code into function.php is not a solution unless it produces a PO File.