P.F. Chang’s stands for the names of its two founders: Paul Fleming and Philip Chiang. The restaurant name combines Fleming’s initials with Chiang’s surname, so it is not a phrase, acronym, or hidden slogan.
The chain opened in 1993 and is known as an American casual dining restaurant serving Asian-inspired cuisine. The brand’s official history describes it as a partnership that put the founders’ names at the center of the restaurant identity.
So the simple answer is: P.F. = Paul Fleming, and Chang’s = Philip Chiang.