[Right Wing Professor]

It means, in a nutshell, that certain biological systems cannot function until all individual components exist, eliminating the possibility of evolution of the system.

Name one such system.

[garybob]

Name one such system.

Humans

[PhilipFreneau]

>>>Name one such system.<<<

There are many, some traditionally referred to as Black Boxes. See:
http://www.actionbioscience.org/evolution/nhmag.html