In the US, the term means much the same as a detailed quantity takeoff. In other countries, a quantity surveyor is a separate profession.
Some GCs and owners hire a firm to do a quantity survey. The result is a list of quantities by trade or by spec division.
If someone hands you a quantity survey, find out who made it and from which drawings. Check its date against the addenda.
Spot check several lines against your own measurement. Bid from quantities you trust, because your price stands on them.