Student or Learner
I would like to know the meaning of "It and that" in the next sentence.
Just press the button. It is as simple as that.
"it" refers to something not present in the example.
A: How do I call a nurse?
B: Just press the button. It's as simply as that.
In this case, "it" means "calling a nurse". Calling a nurse is as simple as pressing the button.
I don't think ymnisky's example of "Pressing the button is as simple as pressing the button" is wrong, but it's probably not a very useful concept.