Different businesses uses the different terms for sending an estimate to the customer. They also call Quote or Pro Forma Invoice.
What is an Estimate Bill?
You as a seller or service provider generate an expected bill to the buyer to give an estimation about your cost, quantity, materials would be dispatched, taxes, shipping charges and other costing which may include in a deal. This is basically presented before the payment is processed by the customer/buyer.
Managing, Adding and Editing Estimates
The feature and functionalities of estimate is as same as Invoice. So you can refer the document of Invoice
Just the heading of the bill will be replaced with Estimate/Quotation instead of Invoice.