It doesn't work. It's my player script

What about it doesn't work? What do you expect to happen and how are you calling this win() method?

GameTab Hi! Please consider adding more info.
Looking at your code, I can see that no variable coins is defined - try this:

extends KinematicBody2D

var coins = 0

func win():
	if coins == 2:
		Player.global_position = Vector2(0, 0)

I am not sure if this is the problem, but it should fix code errors you have!