Take a look at your sidestand, if you hold you bike up and give the kickstand a nuge... very near the pivot a pin will pop out. on the other side is the switch.
there are 2 other safety switches, one on the clutch lever and one on the transmission.
the clutch safety keeps you from starting the engine with the clutch engage. it was very funny when people lerch forward while trying to start their engines.
and the neutral safety does the same thing. when you are in gear and the kick stand is down, you can't start. It was hilarious when people would launch their bikes down the street when they let go of the clutch lever. at least until they started running over some one, usually a congressmen. they don't like being ran over, so they passed a law requiring all manufacturers to make the bikes this way.