is an example of html coding that's used to format text in webpages, like <p> or <br> - it shouldn't appear but sometimes AB goes a bit wonky & we see coding that shouldn't be there.
What beats me is why it keeps on appearing. It should be obvious by now that html no longer works on AnswerBank, so - if a respondent can actually see ' ' in someone else's answer - it should be clear that there's little point in his/her using that code, 'cos it's going to appear again. It actually stands for 'non-breaking space' if I remember rightly. (Mind you, I'm a computer illiterate, so maybe there's some other explanation for its continued appearance.)
There must be a gremlin because it sometimes appears by itself even if it has not actually been typed by the person. I think it even appeared in one of my answers not long ago.