This is the amount of whole lots (see) or parts of lots that your transaction involves. Most often, the amount is shown in the currency in which you are trading. For example, in a transaction involving your 1000 dollars, and the broker (see) provides you with the opportunity to trade in an amount 100 times the amount that you have, he is giving you leverage (see) 1:100. It turns out that in the deal, 100 thousand dollars is the size of a whole lot. This data is about volume.
Trading in financial markets involves substantial risks, including complete possible loss of investment capital. This activity is not suitable for all investors. High leverage increases the risk (Risk Disclosure).