A custom Trading View signal is an alert created from a Trading View indicator or chart use to trigger a bot to enter or exit trades, take profits, and stop losses.
3Commas have existing articles on how to create and link these alerts to your bot here:
How to use TradingView custom signals
Reverse your position with TradingView custom signals
You can create buy and sell alerts for an indicator that does not offer them by following this video:
You can even create an indicator from any Trading View strategy here, so that you can use it for alerts, by following the instructions in our video: