Unreal Actor Blueprints have a feature called Event Dispatchers:
An Event Dispatcher, as the name suggests, sends events.
Events can be consumed by other Actors- each event acting like a trigger for a wide variety of other actor objects.
The example provided by the official documentation uses the scenario of where a final boss dies, opening a door and triggering an explosion:
https://docs.unrealengine.com/4.27/en-US/ProgrammingAndScripting/ActorCommunication/EventDispatcherQuickStart/
For the purposes of this document, Event Dispatches have two main functions we care about:
Bind
keyword.Call
keyword.When the player character (called BP_ThirdPersonCharacter) collides with this actor (Event ActorBeginOverlap), trigger an event (Call On Player Triggered Platform)
When the actor is created (Event Begin Play) subscribe the above event (Bind Event to On Player Triggered Platform)
Bind = subscribe to event, Call = trigger event. Easy.