Sales proceeds or Gross Proceeds are the total amount you received from the item sale. If the item was securities, such as stock sales, they're usually reported on box 1d of Form 1099-B or on a consolidated broker's statement. If the item wasn't reported on a 1099-B, then enter the amount you received for the sale of the item.
Usually your proceeds amount has fees, commissions, or other costs associated with the sale subtracted from it, but if it doesn't, enter them later when we ask about any sales expenses.