Check out example codes for "how to make a singleton in unity". It will help you in understanding the concepts better.

Code Example 1

void Awake()
 {
   if (instance == null)
     instance = this;
   else if (instance != this)
     Destroy(gameObject);
 }

Code Example 2

#region Singleton

void Awake()
{
	if (instance == null)
	{
		instance = this;
	}
	else
	{
		Destroy(gameObject);
		return;
	}

	DontDestroyOnLoad(gameObject);
}

#endregion

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