What is an action and what can happen on screen?
An action is a rule: when this happens (a specific gift, a follow, a sub, bits, a raid, a chat command…) on TikTok, Twitch or Kick, do that. Each action can be for one network or for all of them.
What it can do: an alert with text, icon and colour; an image or GIF (you can also search Giphy); a video; an animation of one of your Avatars; a sound (also from MyInstants); read a message out loud; or something inside a game.
When you create it, it's added by itself to the selected scene, hidden: show it in Scenes to place it and customize it. With Test you fire it with test data to see how it looks.
Tip: Images, videos and sounds are copied to Studio's folder on your computer: they aren't uploaded anywhere and work offline.