It means to talk quickly and incessantly, often about trivial matters, in a way that can be considered foolish or annoying.
Here are some examples:
* "She just rattled on about her new shoes for an hour."
* "He rattled on about the weather, ignoring my attempts to change the subject."
The word "ratchet" itself doesn't have a direct connection to talking quickly or foolishly. It's a mechanical device that produces a clicking sound when moved.
Let me know if you have any other word puzzles you'd like help with!