The vertical bar text token (%|%) is a special token used with the Insert Text action which adds a sequence of left arrow keystrokes to the end of the action to (attempt to) position the insertion cursor at the desired spot. For example:
Insert Text: Sally said "%|%" to Nikola.
After inserting the text, Keyboard Maestro will left arrow 12 times (in this case) to return the cursor to the desired location within the quotation.
When the text is known, you could simply add the 12 arrow keys yourself, but if the text was variable, eg:
Insert Text: Sally said "%|%" to %Variable%Name%.
it becomes much more difficult and this token becomes valuable.