Meanings
Perhaps from the image of ducklings following their mother in an orderly line. See also line up one's ducks.
How to pronounce "have one's ducks in a row":
AU
To be organized; to have one's affairs in order; specifically, to have a multi-person effort coordinated towards the exact same goal.
Example: "Wouldn't it be nice to have our ducks in a row and not have to search for the papers every time we needed them?"