When I call my script2 in script1 it makes script2 global? It stops me from accessing script2's methods at all.

I try to access my Shield script in my PlayerController script just like I usually do:

 using UnityEngine;
 using System.Collections;
 
 public class PlayerController : MonoBehaviour {
     
     private LivesKeeper livesKeeper;
     private Shield shield;
 
     void Awake(){
         livesKeeper = GameObject.FindObjectOfType<LivesKeeper>();
         shield = GameObject.FindObjectOfType<Shield>();
     }
 }

Now, the LivesKeeper script is called in as usual, when I hover over livesKeeper the pop-up says "LivesKeeper livesKeeper" but when I hover over shield the pop-up says "Global::Shield shield".

I have no idea what that means, and when I try to access a public method in the Shield script unity gives me an error in the console that states:

"NullReferenceException: Object reference not set to an instance of an object PlayerController.Shield () (at Assets/Scripts/PlayerController.cs:133) PlayerController.OnTriggerEnter2D (UnityEngine.Collider2D col) (at Assets/Scripts/PlayerController.cs:95)"

PlayerController.cs:95 refers to when I call the Shield() method in my PlayerController script after the shield power-up collides with the player ship. The shield appears just fine and exactly where I want it. Here is my Shield() method.

 public void Shield(){
         if(ScoreKeeper.score >= 13000){
             Debug.Log ("ShieldLvl3 Active");
             shieldLvl = 3;
             Instantiate(shield3, transform.position, Quaternion.identity);
             shield.ShieldActive();
         }else if(ScoreKeeper.score >= 8000){
             Debug.Log ("ShieldLvl2 Active");
             shieldLvl = 2;
             Instantiate(shield2, transform.position, Quaternion.identity);
             shield.ShieldActive();
         }else{
             Debug.Log ("ShieldLvl1 Active");
             shieldLvl = 1;
             Instantiate(shield1, transform.position, Quaternion.identity);
             shield.ShieldActive();
         }

PlayerController.cs:133 refers to the 'shield.ShieldActive();' line. The Shield script is a component of the shield I instaniate in the previous line of the code. I don't understand why it cannot access my Shield script or why it says it is global. Here is my entire Shield script, maybe the issue is in it...

 using UnityEngine;
 using System.Collections;
 
 public class Shield : MonoBehaviour {
     
     public Sprite[] shields;
     public int maxHits = 0;
     
     private PlayerController player;
     private Vector3 playerToShieldVector;
     private int timesHit = 0;
     
     void Awake () {
         player = GameObject.FindObjectOfType<PlayerController>();
         playerToShieldVector = this.transform.position - player.transform.position;
     }
     
     void Update () {
         //lock shield above player ship
         this.transform.position = player.transform.position + playerToShieldVector;
     }
     
     public void ShieldActive(){
         if(player.shieldLvl == 3){
             maxHits = 3;
         }else if(player.shieldLvl == 2){
             maxHits = 2;
         }else{
             maxHits = 1;
         }
     }
     
     void OnTriggerEnter2D(Collider2D col){
         Destroy(col.gameObject);
         if(timesHit == maxHits - 1){
             this.gameObject.SetActive(false);
         }else{
             timesHit++;
             LoadSprite();
         }
     }
     
     void LoadSprite(){
         if(timesHit == 1){
             this.GetComponent<SpriteRenderer>().sprite = shields[0];
         }else if(timesHit == 2){
             this.GetComponent<SpriteRenderer>().sprite = shields[1];
         }else {
             Debug.LogError("Shield sprite missing");
         }
     }
 }
 

Why is this happening to Shield but not to LivesKeeper and is it the reason why I cannot access the Shield methods through my PlayerController script?