If you make sales order for 10 products and than 8 products delivered that will be recorded in delivery note. And from that 8 product you can make invoice. And here you can't invoice for remaining 2 products.

And also you can invoice for 6 products,  than only you can record payment of 6 products.

The FA sequence is like this.
1. Sales order
2. Sales delivery
3. Sales Invoice
4. Customer payment.

Alternatively  with prepaid orders
1. Prepaid sales order
2. Record payment
3. No delivery. But directly invoice for that sales order

That's the sequence. Hope I explained the flow clearly.

Is there any report that indicates the pending invoices, that is, if I made a delivery order, where if I was going to deliver 10 products, when I invoice, I want to indicate that I only invoice 8, where I can see that they are still pending invoicing 2 products?

Thanks