Understanding the components of flows
Triggers are essentially if-then functions that tip off a defined process in your workflow. For example, if a new email is received (trigger), you can set an action to tag the email by analyzing its content (action 1) and then forward it to the relevant department (action 2).
You are free to set your trigger to whatever event would otherwise be the signal to begin a normally repetitive manual process.
Here's how setting up a Gmail trigger works:
To learn more about setting up a Flow, click here.
To learn what actions are, click here.