It has [A]/[B] printed on it, where [A] is LCD inside a box and [B] is a monitor symbol. Pressing it just turns the screen off for a second then back on.
Also, what does fn-f9 do? It looks like a square with a diagonal through it and two smaller squares inside. Pressing it does nothing as far as I can tell.
2 Answers
Judging by your descriptions fn-F8 would switch the output to an external monitor if one were plugged in and fn-F9 would enable/disable the trackpad.
Test it, and let me know!
2Fn then F8 brings connects a TV via the HDMI cable.
The first time displays a laptop the second press shows a HDMI cable graphic and connects to the TV. I have yet to get the audio to work but video is fine.
