There is only one "IF" function so I assume you mean Excel Functions in general
in combination with the "IF" function.

Peter Nonely has a function dictionary, available from Rod de
Bruin's site, at http://www.rondebruin.nl/files/xlfdic01.zip .

Gord Dibben  MS Excel MVP

You could start with Excel's own help.

There isn't much to learn about IF. The syntax is

=IF(test,result_if_true,result_if_false)

where test is any expression or cell value that returns a numeric
or Boolean result. If test is TRUE or non-zero, IF returns
result_if_true. Otherwise, it returns result_if_false. Both
result_if_true and result_if_false can be anything you want.
E.g.,

=IF(A1>10,"Greater","Not Greater")