When two cells in a house hold only the same two candidates, no other cell in the house can use those two digits.
On a Kropki board this works exactly as in Classic. The examples are from Kropki puzzles on this site. The dots often make the pair, by cutting two neighbours down to the same two digits.
Worked examples
A position from a real Kropki puzzle on this site. Step through it: the board lights what each step talks about, and the arrows show what rules what out.
A pair in a box
In box 5, look for two cells that hold the same two candidates between them.
Where it fits
HardNaked Pair is a Hard technique: Hard Kropki puzzles are the first to need it.
The Classic Naked Pair lesson teaches it on a plain 9×9 board. The Kropki overview explains the rule and the levels.
Naked Pair in the other styles: Sudoku X, Jigsaw, Thermo, Windoku, Arrow.
Try it on a Hard Kropki puzzle. Next Step points it out when it is the move.