Hi there!

The +/- button you are referring to is called the "Group" button in Excel. It allows you to collapse and expand rows or columns to make your worksheet more organized and easier to navigate.

To add this button to your desired rows or columns, follow these steps:

1. Select the rows or columns that you want to group together.
2. Right-click on the selected rows or columns and choose "Group" from the drop-down menu.
3. The +/- button should now appear above the row or column label heading.

To collapse or expand the grouped rows or columns, simply click on the +/- button.

You can also use the keyboard shortcut "Alt + Shift + Right Arrow" to group selected columns or "Alt + Shift + Down Arrow" to group selected rows.