Question what tf is an array

hey guys as you can tell im a raging beginner
I was following this flappy bird tutorial but couldn't understand how an 'array' can be used to animate
what is an array
pls no hate

Code (CSharp):

1.     private void AnimateSprite()
2.     {
3.         spriteIndex++;
4.         if (spriteIndex >= sprites.Length)
5.         {
6.             spriteIndex = 0;
7.         }
8.  
9.         spriteRenderer.sprite = sprites[spriteIndex];
10.  
11.     }

also what's sprites.Length

thank you so much

 

https://www.google.com/search?q=what+is+an+array

 

Godsend