When the rotary switch for my lights is rotated all the way counter clock wise, it can be pushed in. It "clicks" like a switch activating and de-activating. What function is this controlling?

The exterior light switch has to "P" position all the way to the left turns on the left standing light, to the right of the "P" position the right standing light is tuned on and it is meant for when you park, if you park so the driver's side is to the curb you turn the exterior light to the right of the "P" position so other driver's can see you and to the left of the left of the "P" position if you park passenger side close to the curb so the left standing light turns on.