You have 2 options.
1. Paper Trading. It was designed to execute simulated trading on TradingView, without risking real money. To practice trading using Paper Trading, first open a chart. Next, open Trading Panel and select Paper Trading among the brokers.
2. Broker's demo account. Most of the brokers supported in TradingView provide demo accounts, that can be used for trading. To do this, you must first create the demo account on the broker's website. Next, select the broker in the bottom Trading Panel of your chart and log in using the credentials of your broker's demo account.