My coin count resets to 0 after every death
Like Galactian said with the absolute minimum words possible, globals.
Globals are a behavior that you can find in the Logic & Maths section. This behavior can store values between levels or level resets. This behavior does not save if you reload the tab. If you wanted it to save between play sessions, the Save behavior would be required.
Note: Whenever you update the value of a Global, all Globals with the same name will output.