Why isn't a return statement needed in this particular case?

Link to exercice: https://www.codecademy.com/courses/learn-java/projects/build-a-droid

I don’t understand why a return statment isn’t needed for int transferAmount in the "// method in question". Thank you for your help.

public class Droid{
String name;
 int batteryLevel = 100;

 // Constractor method
	 public Droid(String droidName){
    name = droidName;    
 //method in question
  public void energyTransfer(Droid Droid1, int transfer, Droid Droid2){
// Why isnt a return needed for int transferAmount? This is the thing I dont understand.
    int transferAmount = transfer + 10; 
 // Why isnt a return needed for int transferAmount?

  // ignore this, just putting the whole method  
    Droid1.batteryLevel = Droid1.batteryLevel - transfer; 
    Droid2.batteryLevel = Droid2.batteryLevel + transfer; 
  System.out.println("Alex's energy is now: " +Droid1.batteryLevel + " Codey's energy is now: " +Droid2.batteryLevel);
//main method
 public static void main(String[] args){
    Droid Codey = new Droid("Codey");
    Droid Alex = new Droid("Alex");
    Codey.energyTransfer(Codey, 10, Alex);

Why would it?
The energyTransfer method is a void method meaning it doesn’t have a return value. It simply does something
Within that method a local variable transferAmount is set to transfer + 10
Setting a variable has nothing to do with returns.
I think you have some confusion about return