Display cables usually have PINS, and Macintosh Computer Display adapters usually have HOLES.
When your Mac supplies a VGA, but your monitor has an older two-row Macintosh display cable, you need either of the top two adapters listed in the article Jim referenced above.
33001- Monitor and Display Adapter Table
These are different from the majority of similar adapters because they have PINS on the VGA side, to plug into a computer or adapter, and HOLES on the Macintosh side, to accept a Macintosh display cable.
The third adapter in that table adapts a VGA monitor to an older Macintosh display. It is not what you want. Its has HOLES on the VGA side, to accept a VGA display cable, and PINS on the Macintosh side, to plug into the Macintosh.