You can open as many windows of TradingView Desktop as you need. Usually, multiple windows are used in multi-display configurations, so you can have a dedicated app window for each display in your configuration.
You can open a new window with either the New Window button on the window title bar or the app menu.
Having a new window opened, you can move it to another display. The TradingView Desktop app restores all windows and their positions from the previous session upon an app launch, but you should use the Exit function instead of closing all windows one by one. Read more about that in this article.