A "Zeigende Paare" strategy applies when a candidate within a 3x3 block appears only two times, and both instances fall on the same row or column. Das bedeutet the solution for that candidate within this block must be in one of those two cells. Daher, you can remove that candidate from the Notizen of all other cells in that row or column outside of the block.
To better understand "Zeigende Paare", let's look at an example.
Schauen wir uns an the top-left block. All the cells that could possibly contain the number 4 are in a single column. Since the number 4 must appear at least once in this block, one of the highlighted cells must contain the 4.
From this, we can safely eliminate the possibility of 4 being in any of the other cells in this column.
Remember that you can use the same technique for blocks, rows, and columns.
Das ist the "Zeigende Paare" solving method. Now you can move on to the next Sudoku strategy below, "Zeigende Dreifache."