Yes, a non-breaking space (sometimes called a 'hard space') is used between words that you want to keep together on the same line and not get separated by wordwrap at the end of a line. In most word processors you enter a non-breaking space by pressing ctrl-space.
In HTML code it is an ampersand & followed by nbsp.
To answer peppermum's question, posts to bulletin boards/forums often allow the user to define a 'signature' that appears at the end of every post. Your friend must have tried to do that and has pressed ctrl-space as (part of) her signature. She can cure it by going into her profile and editing her signature and delete whatever is there and retype it without the hard space.