How to add game over UI after collision?

Hello, Im new to Unity. Im making my first game and i want to add a game over screen after the player collides with the object. I dont know how though. I’ve searched literally every corner of google for an answer but cannot find one. The UI is just called GameOver, but i dont know how to enable it after the collision. Heres the collision code:
using UnityEngine;

public class PlayerCollision : MonoBehaviour { 

    
    public playermovement movement;
    

     void OnCollisionEnter (Collision collisionInfo)
    {
        if (collisionInfo.collider.tag == "Obstacle")
        {
            movement.enabled = false;
            
        }
        

    }
   

    
}

Before the OnCollisionEnter call, add a line that says public GameObject GameOver. Set the GameOver reference to your UI object in Unity’s inspector. After the line that says movement.enabled = false;, add this line: GameOver.SetActive(true); .