Once the two are connected with the arrow, select the Action "Filter a list e.g. CSV". Next, select the reference like in the example csv1. In this case, we use the reference to the previous connector without curly brackets {{ }}. Within the file condition, you can use standard Python filtering language, while each column is referenced by the word item in combination with a number, starting at zero. So in essence item[0] references the first column, item[1] the 2nd one, and so on.