Let's assume we're looking at the tblSales table and
trying to find the Account that appears most often.
Open a new query in Design view and select the tblSales table.
Drag the [Account] field down three times (yes, three times)
Click on View > Totals to display the Totals line for each field.
For the first [Account] field, select "First" in the Totals line.
For the second [Account] field, select "Group By" in the Totals line
For the third [Account] field, select "Count" in the Totals line
Also for the third [Account] field, SortDescending.