The vernacular language is Shanghainese, a dialect of Wu
Chinese; while the official language is Standard Mandarin. The
local dialect is mutually unintelligible with Mandarin, and is an
inseparable part of the Shanghainese identity. The Shanghainese
dialect today is a mixture of standard Wu Chinese as spoken in
Suzhou, with the dialects of Ningbo and other nearby regions whose
peoples have migrated to Shanghai in large numbers since the 20th
Century.
Nearly all Shanghainese under the age of 40 can speak Mandarin
fluently. Fluency in foreign languages is unevenly distributed.
Most senior residents who received a university education before
the revolution, and those who worked in foreign enterprises, can
speak English. Those under the age of 26 have had contact with
English since primary school, as English is taught as a mandatory
course starting at Grade 1. (wikipedia.org)