The maximum number of contracts refers to the highest allowed position, represented as an absolute value, that you can occupy at any given time. The size of your account determines the number of contracts you can trade.
For example, if your maximum number of contracts is 8, you can simultaneously trade 4 contracts on the NG and another 4 contracts on the E-Mini S&P 500. It is important to note that exceeding the maximum number of contracts allowed for your account may result in to violations of risk management protocols and potentially resulting in significant losses.