New to collecting - easy question

[AP914]

I'm very new to collecting so please excuse my simple question.

I am confused on the numbering of some cards. Example for 2014 Donruss Diamond Kings Season Stat Line Parallel Set the first card is #1 Bryce Harper. This is followed by #/20. Can someone explain what the #/20 means? Does it actually mean there are only 20 Bryce Harper cards out there in existence? That just doesn't seem right. If that is correct does that also mean that there can only be 18 complete sets in existence because Chase Utley (card 19) is followed by #/18?

Any explanation is greatly appreciated, and again excuse my naiveness.

[revghost]

It means that for that card, the 2014 Diamond King Season Stat Line Parallel Bryce Harper #1, there are only 20 copies. The /20 is a print run for that specific parallel "Stat Line"and has nothing to do with the player on the card. The Utley Statline should be numbered /20 as the number relates to the print run for the parallel level.