Really basic health and damage script

Hello,I just started re learning unity from a long break..and I am trying to start by doing a basic shooter.The player controls something like a turret (or even a mech later).However,I tried using a few basic health and damage scripts (Js) but some of them were too complicated for me,others came with more than enough errors to get me confused.I do have my player shoot script,and my enemy is going to be just some cubes.Could someone please show me the most basic,simple method for doing a health and damage script?I really would appreciate it,may it be only 3 lines of code.

 

The official Survival Shooter tutorial does a better job than I could of walking you through setting this all up.