is often superficially summarized as "aboutness". Beliefs, desires, etc. often have an object that they are about; e.g. "I believe that Johnny is alive
". This is thought to be important, and perhaps something that a machine could never achieve.
Note that intentionality (-tion-) is not to be confused with intensionality (-sion-), a concept from semantics.
See also: Chinese Room, Thomas Nagel, consciousness, mind-body problem, John Searle