A sales quote is an estimated amount that a person selling something gives to a customer. It is given to show them how much it would cost to have the work done. Many services do not have fixed prices for work. The cost can change depending on the tools, materials and how much work is needed to be done for each customer. The person calculates an estimated amount, and gives this to the customer, so that they can have an idea how much it will cost.
The sales quote is figured from the information, given by the potential customer, about the work they would like to have done.