I have a column with cells that contain the results of a formula:
=IF(B8=B9,"",B9)
In some cases the value is blank (""), in others the value is filled.
When I try to count the values using COUNTA, the resulting count
includes the cells where the formula result is "". How do I count only
the cells that have a value other than ""?

Maybe COUNTBLANK() will help. It counts empty cells, including those with a
formula that returns empty text.

Subtracting COUNTBLANK() from the total number of cells would count the
cells that have a value other than "".