Hi EllenOJD,

That small black arrow you're seeing on the filter button in Excel 2007 is called the "second small arrow" or the "filter by selection" arrow. It's a useful feature that allows you to filter your data based on a specific cell value or range of values.

Here's how it works:

1. Select the column you want to filter.
2. Click on the filter button in the ribbon or toolbar.
3. Click on the second small arrow to the right of the filter arrow.
4. Click on the cell value or range of values you want to filter by.
5. Excel will filter your data to show only the rows that match your selection.

For example, if you have a column of sales data and you want to filter by a specific salesperson, you can use the second small arrow to select their name from the list of values in the column. Excel will then filter the data to show only the rows where that salesperson made a sale.