Manipulating one variable in a different script.

Hi! Hope i can be clear enough

 public Class Script1 : Monobeaviour
 {
     public int variable = 10;
 }

  public Class PlayerInfo: Monobeaviour
  {
      // reference to the gameobject
      public GameObject gameMechanics_GO;
      // local variable, reference to the mainGame Script
      private MainGame mainGameScript;
      private void Start()
      {
          // create the reference
          mainGameScript = gameMechanics_GO.GetComponent<MainGame>();
          Debug.Log(mainGameScript.life);
      }
  }

attach the script to the correct gameObjects and don't forget to drag the manager gameobject to the reference on the player's script... now you can reference the mainGameScript to edit the life variable and you don't need to add a local variable to copy it.. just use the reference

Hope this helps!