Do -1 to scene variable thing

How do I create the ‘Do’ thing at the top and bottom of the image in the action area?
https://forum.gdevelop.io/uploads/default/original/2X/6/63d6f5ea6b691c349a227ca0d326666b50e737b7.jpeg

01

Thank you but how would I actually create that whole thing of code?

Explain in more detail what exactly you want to code and how it should work

I want to be able to take one heart away every time I collide with lava or any other enemy and go back to the start when I collide with lava or other enemy and also go to game over screen when my three hearts are empty

You can use Resource bar ( serarated units ) for this. It allows you to set a value instead of managing the creation and deletion of individual objects.

Resource bar (separated units) - GDevelop documentation.