How do I make a global instance?

I want to make so that when all the enemies are destroyed, text comes on the screen. I have currently an amount instance on every enemy, and when an enemy is destroyed, it will drain one. When it reaches 0, it should display a text that says ''You win!''. So how do I do this right? When I kill an enemy, it only drains the ''Amount'' instance that is only on the enemy who is destroyed. So how do I make a global variable?

Solved it, I just had to create it to the player!

Ok.

I have a similar current project.