This method works when notes with the same number occur twice in the same row or column of a 3x3 block. Such an occurrence means that this number is the solution for one of the two cells in this block. Therefore, you can remove this number from the other cells of the row or column.
See the example below. In a 3x3 block, in the top row we see cells with repeating values - 1 and 1, 9 and 9. There are no other repeating numbers in the block, so these numbers can be considered "indicating twos". This means that you can remove other occurrences of 1 or 9 from the row, which we did in the second screenshot.
The "Pointing Twos" method belongs to the advanced ones and is well suited for solving not only easy sudoku, but also medium and hard levels. Once you've learned the specifics of this method, you can move on to a more complex one - "Pointing Triples".