How to create a Security Action that sends an email to the Admin with Backand?

How can I create an Action that will send an email to the Admin users when the user hits a specific button?

You can send the email with two options:

1. After an event of Create or Update of an object
2. By calling server side code which called on-demand action

In the first method, it assuming the button creates a new row in an object, in this case add After Create event and send the email to the Admin

In the second method, there is no object, so you make REST API call to invoke the server side action which will send the email.