Hm.. most things are already said here, but it sometimes helps if people say it in a different way:
1)
You put something onto your scanner - the scanner takes something like a high resolution image of it and stores it in a certain file format on your computer. This is often pdf, jpg, png, ... It didn't matter what you scanned - those are just images to your computer. This means, if it's text, you cannot edit that text. If it's an image you could open it with Photoshop or something like that, and work on it.
2) As previously mentioned: Some scanners come with OCR software, still take a picture of the text you are trying to scan and tries to "read" the text and converts the image into a word document. That war you can edit the text. I have tried that before - doesn't really work super well in my opinion.
Hope that helps to clear things up a bit for you...
Cheers!