This feature is included in the monthly subscription price. It gives you the opportunity to test your strategies without spending real money. Trade is conducted "on paper". All orders will be displayed in the tab "My tasks", where you can analyze the results.
Initial virtual balance = 1 BTC. The virtual balance does not end. You can safely test your most aggressive strategies with no risk.
The strategy testing mode can be enabled in the settings. At the same time, by adding a new task, you can disable this feature. In this case, orders will be real and for real funds.