Cash against document means that you ship the goods to the foreign country. The documents (Bill of Lading and invoices) are sent to your client’s bank. The client must pay for the goods before the documents are released. This will work in countries where you can trust the banks. The advantage is that the client does not get access to the goods without paying. The drawback is that if they change their mind and do not want the goods, you have to bring them back and pay for the shipping.