When two cells in a region hold only the same two candidates, those digits belong to those two cells.
Where to lookA pointer first: in the bottom-right box, 2 cells can only hold the same 2 digits.Naked pairIn the bottom-right box, row 7, column 7 and row 8, column 9 can only hold 4 and 8, so those digits must go in those cells. No other cell in the bottom-right box can be 4 or 8.
Look in a row, column or box for two cells with exactly two candidates, the same two. Those digits fill those cells, so remove them from the region's other cells.
This example, step by step
Where to lookA pointer first: in the bottom-right box, 2 cells can only hold the same 2 digits.
Naked pairIn the bottom-right box, row 7, column 7 and row 8, column 9 can only hold 4 and 8, so those digits must go in those cells. No other cell in the bottom-right box can be 4 or 8.
In hints
The hint marks the two cells and their digits, and strikes those digits from the region's other cells in orange.