"Pointing triples" technique is very similar to "Pointing pairs". It applies if a Note is present in only three cells of a 3x3 block and also belongs to the same row or column. This means that the Note must be a solution for one of these three cells in the block. So, obviously it can't be a solution of any other cell in the row or column and can be eliminated from them.
Let's take a look at the bottom right corner. In this block all the cells that might contain number 1 are located in one row. As number 1 must appear in the bottom right block at least once, one of the highlighted cells will surely contain 1.
After this conclusion all other possible numbers 1 can be safely deleted from the Notes of this row to avoid confusion.
Remember that you can do the same trick for blocks, rows, and columns.
That is how "Pointing Triples" technique works. Once you have learned it, you can get some practice.