Instantiate objects

For my game (as part of a school assignment)
i am making a penguin npc that will clone itself and attack players.
Using instantiate, but honestly have no idea how to use it.
The 0f in line 9 (subbing for rotation) is confusing me and i have no idea what to replace it with
Any help is appreciated, since i dont actually know what the instantiate page is talking about.

Ty

using UnityEngine;
using System.Collections;

public class Penguinspawner : MonoBehaviour {

public GameObject Penguin;
public bool Alive = true;
private GameObject PenguinClone;

// Use this for initialization
void Start () {

    Vector3 test = new Vector3(0f, 0f, 0f);
    PenguinClone = Instantiate(Penguin, test, 0f);

}

// Update is called once per frame
void Update () {

}

}

The 3rd argument for the Instantiate overload you’re using is a rotational value defined as a Quaternion. For a zero rotation, you can simply use Quaternion.identity. So…

Instantiate(Penguin, test, Quaternion.identity);