Reference: The relation between a term, statement, symbol, gesture or sign and whatever it stands for. The latter is called the referent of the term, statement, symbol, gesture or sign.
The main two points to notice is that one needs some term to speak about whatever terms etc. stand for, and that "reference" and "referent" are useful here, and that it is not claimed when saying that "a refers to b" that whatever is meant by "b" exists. In case whatever is meant by "b" does exist "a" is said to denote it.
One reason the relation of reference - as defined - is useful is that it happens quite often that one just does not know (yet) whether a term denotes.
Terminological note: What matters here is the idea defined and the contrast between reference and denotation, but not the actual names one uses - and indeed usage in this respect is conflicting.
I tend to use "reference" and "meaning" as synomyms.