It is a comprehensive list of quantified items, listed by trade, for everything needed to build the specific house according to the plans.  If you don’t plan to request a quantity surveyor to draw up a bill of quantities for you, you can ask the builder to provide it for you with his quotation. Reputable builders will be willing to do this for you, if you are serious about the building project. Take into consideration that it is a lot of work on the builder’s side and that it will take some time to draw up.