Learn a little about it here:
The Cessna Citation X (X as in the Roman numeral for 10, not the letter) is a medium-sized business jet aircraft and it is the fastest business jet and fastest currently flying civilian airplane in the world, traveling up to Mach 0.92 (703 mph). The Citation X is powered by two Rolls-Royce turbofan engines and is built by the Cessna Aircraft Company in Wichita, Kansas. The Citation brand of business jets encompasses six distinct "families" of aircraft, one of which is the X, as it was a completely new design, not a derivative of earlier Citations.
Taking myself up on my own advice, I am already trying to study for the eventual training. The usual term for learning a new aircraft is "drinking from a firehose." There's always a lot of information coming at one very quickly, and it's a struggle to keep up. The more I know going in, the better!