It's actually an and sign, followed by the word amp (short for ampersand), followed by a semicolon, like this:
&
That whole sequence represents an and sign (&). I know that seems like a waste of time, because it contains an and sign! But other symbols, e.g. a quote, can be represented in a similar way (a quote is an & followed by the word quot followed by a semicolon, i.e. " ). More details here: