It refers to the finger tip single-wipe operaration, where the control lever is tipped/tapped/moved against a spring.
The other positions (intermittent, normal, fast) are not sprung: the lever stays where it is put.
In my Skoda Octavia, the lever is tapped in the downward direction to get a single wipe. The other settings are in the upward direction.
Judging by the similarity to my Octavia's intake system (which is also a TSI engine) it is a simple cover that redirects intake air flow from the open parts around the bottom of the housing back down through the round opening in the centre and though the pipe into the the air cleaner. Mine comes via a pipe off of the the left hand side of the missing cover ...