Creating a Customer Invoices in Odoo Financial Accounting Module?

Customer Invoices.

You can view the existing customer invoices which are generated from Sales Orders and you can create new Customer Invoices directly from here

Accounting>Customers>Customer Invoices

After selecting the invoice you can validate, register payment, refund invoice, etc can be done from here.

In the above window you need to select payment method through you received the payment from the customer.