ID attribute and Labels

OK, so im on chapter 7 of the jon duckett HTML&CSS book, its about forms. What has me stuck right now are the label element and the id attribute. What exactly does the label element do, and what is the ID attribute for??
About labels, the book says that each form control should have its own label element as this makes the form accessible to visually impaired users. So, am i supposed to use it for that purpose…?? I know that it creates text above, to the right, and to the left of boxes (i think), but i am so confused on what this element is meant for. Is its sole purpose to help aid screen readers, or does it do that in addition to the text stuff?
The ID attribute says that its used to “identify the form from other elements on the page” and that it can be used on any form control. I straight up have absolutely no idea whtsoEVER what this is. Im completely lost on this one. As far as creating a form, what do i use these two things for?

It has at least one more use besides adding text. Giving same for attribute to labels and giving id attributes “match” them up together. Meaning that if you have a checkbox or radio box then you can click on corresponding labels to check off matching checkbox/radiobox.

Here is some good info.