The "Pointing Triples" solving method is very similar to the "Pointing Pairs."
A "Pointing Triples" applies if a candidate appears only in three cells of a 3x3 block, and all three of those cells belong to the same row or column. This means the solution for that candidate within this block must be in one of these three cells. Therefore, it obviously cannot be the solution for any other cell in that row or column, and it can be eliminated from them.
For example:
Let's look at the bottom-right block. In this block, all the cells that could possibly contain the number 1 are in a single row. Since the number 1 must appear at least once in the bottom-right block, one of the highlighted cells must contain the 1.
After reaching this conclusion, you can safely remove all other possible instances of the number 1 from the notes in this row to avoid confusion.
Remember that you can use the same technique for blocks, rows, and columns.
This is the principle of the "Pointing Triples" solving method. After you have learned it, you can get some practice.