You can add Player to a Global Script:
1- Make a new script and name it Global.gd
2- In Global.gd, make a new variable and call it Player, so your Global.gd will look like:
extends Node
var Player
3- Go to Project->Project Settings->Auto Load and add Global.gd to the list
3- In your Player’s _ready() function, add :
Global.Player = self
Now, just connect the body_entered signal to your current node script and within your current node script, call the Player function you want, like: