When you scan in a document, it what you get is a picture. Essentially, a
bunch of independent dots. Programs such as spreadshetts and word processors
operate on characters, a character is a set of binary 1's and 0's in a
particular patter that identifies the particular character. Different
computer systems use different codes for various characters, but common ones
are ASCII and Unicode.
OCR stands for Optical Character Recognition. An OCR program analizes a
picture to find patterns that it recognizes as characters, and translates the
picture to lines of characters that can be used by character-oriented
programs. OCR progrmams can make mistakes, so you need to look at the
converted document and not just assume it's ok.
If the document was originally in character format, it would be better if
you could obtain it more directly than scanning; eg., in an e-mail or an
attachment to an e-mail.