When I tapped it, the speaker got a little x over it, but it didn't seem to change anything. Icon popped up at a stoplight, then went away when I started moving. Looked for it the rest of my drive that night, and saw nothing. Upgraded to 36.2 only two days ago.
It's the chime notification for the park assist. When you get to close to something, the car beeps. You can touch the notification to temporarily mute it (or go to Controls > Safety & Security > Settings > Park Assist Chimes to stop it entirely).
I use this often when I park in my tight garage and the nonstop pinging gets annoying.