HTML5 Canvas Transformations rotate() usage

Question

Hi. Please Explain The Sentence Located Below As Clearly As You Can.

Sentence = "The rotation will only affect drawings made after the rotation is done."

I'm confused. when we want rotate an object, we must use rotate() and of curse before using rotate(), we don't have any rotation on the page ? right ?
so why the sentence above says its affect after rotation !!!
I'm very confused.

Thanks in advance.