SORT()’s array argument is the entire FILTER() function. The sort_index value of 2 sorts by the Value column, the second column in array. The sort_index value is -1, which applies a descending sort.

The syntax for the INDEX function is: INDEX(array, row_num, [column_num]). The array is the range of cells that you’re working with. Row_num is, obviously, the row number in the range that ...

though it's two functions used in concert with one another. First let's look at INDEX. With INDEX, you select an array, and then tell it a number, and INDEX returns that element. So here ...