You find a "strong link" in a row (only two possible 5s in that row) and a "strong link" in a column (only two possible 5s in that column). One end of the row link and one end of the column link share a common box. The other two ends (the "tips" of the kite) do not. You can eliminate candidate '5' from the cell that sees both of those tips.
Use "Naked Pairs" or "Triples" (where 2 or 3 cells in a house contain the same 2 or 3 candidates) to remove those digits from all other cells in that row, column, or block. sudoku 129 better
involving the digits 1, 2, and 9. Mastering these "129 triples" is a hallmark of transitioning from a casual player to an advanced solver. The Power of the 129 Triple In Sudoku, a You find a "strong link" in a row