* St. John, US Virgin Islands: The official language is English. However, you'll also hear Spanish and Creole spoken, especially in informal settings.
* St. John's, Newfoundland and Labrador, Canada: The official language is English.
* St. John, New Brunswick, Canada: The official languages are English and French, with English being more widely spoken.
* St. John's County, Florida, USA: The dominant language is English.
Please specify the St. John you're interested in, and I can give you a more precise answer.