A bill of quantities carries only three things: what is done, in what unit and how much. Prices belong in the estimate, not here.
Who prepares it
Under LBN 501-17 the designer prepares it as part of the building project, alongside drawings and specifications. The form names the object, address and order number, states which part of the project the quantities come from, and lists number, description, unit and quantity, with signatures below.
On private jobs there is often no project at all — then you measure and write it yourself before pricing, which is also the only way to later prove that extra work really was extra.
Two different lists
The designer's bill of quantities has no prices. The tender version adds a unit price, line total, total, VAT and grand total; the client attaches it to the tender documents and bidders return it priced. In the tender version a bidder must include in each priced item every cost needed to carry it out, overheads and profit included, and spread the cost of anything without its own line across the others proportionally.
Measuring
Areas in m², linear elements in metres, countable items in units, concrete and soil in m³, steel in tonnes. Note whether openings are deducted. Laps and offcuts are not quantities — they belong to material purchasing, not to the measured work.
The sequence is always drawings or site measurement → quantities → prices → estimate → overheads and profit → VAT.