You want to jump out of a perfectly good plane? Then you're going to spend quite a lot of time hearing this phrase. Unless you do a Tandem jump which, in comparison, bores the living hell out of you.
Before your first jump you learn just two things in the training: How to recognize a malfunctioning chute, and how to use the cut-away pad and the reserve chute deployment handle. 1
To be more precise: You learn to look, locate, cut - away, reserve, arch. And again. And again. Until it's muscle memory.
Got it? Ok, then you're good to sit in the open door of a plane, see quite a lot of nothing below you, grin in the camera and go. *Insert mad adrenaline rush here*
Back to topic: The reserve chute deployment handle opens your reserve parachute, after you left the main chute behind by cutting away from it. Actually, it's not exactly necessary to open it manually, because it should open automatically when the main parachute bids farewell. But at 5000 feet height in freefall you're rather safe then sorry.
And just in case you just jumped out of a plane without the course, but with a parachute: It's usually the metallic handle on your breast, to the left, just begging to be pulled (all the way down to your crotch, if in doubt).
But don't forget: *First* the cut-away pad (usually on your right side, nice, big, red). Two chutes at the same time are no fun.
1 You also learn how to exit the aircraft, how to steer and how to land, but believe me, that's the part you really care about.