In this image, there are three cells, marked with a red dot, which contain the same 3 candidates. Following the same principle as for naked pairs, these 3 candidates have to be used in these 3 cells and not in the rest of the column and minisquare. These three candidates can be safely eliminated from the cells marked with yellow dots.
It can be tricky to spot a naked triple sometimes. Don't expect there always to be 3 candidates in each of the cells that form the triple. In the following image, one of the cells marked with a red dot has only 2 candidates. The same logic applies, these 3 cells form a triple because there are only 3 candidates that can be used to make up their 3 values.