Instantiating Prefab error C#

Assets/scripts/Explosion.cs(13,66): error CS0119: Expression denotes a `type', where a`variable', `value' or`method group' was expected

 go = (GameObject)Instantiate(Resources.Load("cube_wall"),Vector3(5,5,5),Quaternion.identity);

But if i do the below it's fine. Why? Also, with the below code since i am not specifying the vector. How does it know where it will instantiate in the world?

  go = (GameObject)Instantiate(Resources.Load("cube_wall")

This is occurring because - in c# - you need a "new" keyword before "Vector3".

So, your corrected line should look like this:

go = (GameObject)Instantiate(Resources.Load("cube_wall"), new Vector3(5,5,5), Quaternion.identity);