Crash-Course/Assets/Scripts/HealthBar.cs

using UnityEngine;
using UnityEngine.UI;

public class HealthBar : MonoBehaviour
{
    public Slider slider;

    public void SetMaxHealth(float health)
    {
        if (slider != null)
        {
            slider.maxValue = health;
            slider.value = health;
        }
    }

    public void SetHealth(float health)
    {
        if (slider != null)
        {
            slider.value = health;
        }
    }
}