You're welcome Belleke, and you should be able to update the table now.
Look for the query via the ribbon "Data -> Show Queries" (for Excel 2016). This opens the query pane, then select the one with forPivot in the name, right click and edit. Go through the applied steps at your right. It should make some sense. Don't hesitate to ask for more help.
As it turns out, you can make the same pivot without PQ. Use a tabular lay-out, drag the fields "Bins" (a lookup to the helper table), "date" (which you'd group in months),"activities", and count the "Nr".