the if function is If(criteria, response if true, response if false)
In your formula
criteria D16="" this will be true if there is nothing in D16 or if an
eqauion will give an "" response

\the if true response is that if there is nothing in D16 there wil be
nothing (almost the same as "" but that is a different question) in th ecell
where the equation is

\the if false response is that if there is something in D16, show it here.

In this case the comma is a separator for different sections of the formula.
there are other formulas where the "," could be a text section being looked
for or as a result. for example if you wanted to replace a comma with a
semicolon in some cells you could use
=substitute(a1,",",";").
Inother words "," can have multiple meanings.
"Excel Question" wrote:

this is the formula: =IF(D16="","",D16)

Thank you for your help on this.

"ww" wrote:

It could mean a lot of things depending on the formula. If you give the
complete formula I'm sure someone could help you out.

"Excel Question" wrote:

Could anyone tell me what this means in an excel formula?

what does "," mean in an excel formula