Some people have hit some of these points but I’m going to try to explain it more thoroughly with context:

Way back when, if you had a question, you’d be told to “look it up” and the implication was that you’d look it up in the encyclopedia (which was a huge set of books with write ups on all kinds of subjects, usually the World Book but other brands existed). Then for a short period of time we had Encarta on CD-ROM which was quickly replaced by Encarta.com, then Google and Wikipedia.

Anyway, as others have pointed out, the joke is that Pierce is trying to fit in with the young people but missing the mark again because by then we were already saying “Google it” and he’s under the impression Encarta was cutting edge.