See the Python reference of this logic brick in
The Message Actuator allows the user to send data across a scene, and between scenes themselves, which can be received by other objects to activate them.
Object to broadcast to. Leave blank if broadcast to all (or sending to another scene).
Subject of message. Useful if sending certain types of message, such as “end-game”, to a message sensor listening for “end game”
andQuit Game actuator.
Body of message sent (only read by Python).
User-specified text in body.
You can use the Message Actuator to send data, such as scores to other objects,
or even across scenes! (alternatively use