I assume that what you mean is that you want the Excel spreadsheet column
headings to be different than the field names of the fields you have in your
query.
You can name each individual query field in your query and the export will
use the name you give the field.
For example, assume that your query is based on a table that has a column
called Field1.
If query specifies Field1 as a field to output, the export would label that
column "Field1", which I assume is NOT what you want.
Instead, name the field when you specify it in your query. The query column
for that field would look like this:
Name1:Field1
In this case, the export would have a column heading of Name1 (where Name1
is whatever name you want to give to the field).