It implies that someone is:
* Quick-witted: They can think on their feet and come up with solutions in the moment.
* Resourceful: They know how to use what's available to them to achieve their goals.
* Level-headed: They don't panic under pressure and can make sound decisions.
The phrase is often used to describe someone who is able to navigate a difficult or challenging situation. For example:
* "She had to deal with a flat tire in the middle of nowhere, but she had the where with all to change it herself."
* "When the power went out, he had the where with all to find a flashlight and get the candles lit."
While the phrase is not used in formal writing, it's a common and well-understood expression in everyday conversation.