I like this postcard very much, because it's a multiview with 15 pictures and because of its colors :) It shows the Friesland province in the Netherlands. I only knew there was such province and that a local language was spoken there, but receiving this postcard inspired me to read a bit more :) Here's some information about the Frisian language:
Friesland distinguishes itself from the other eleven provinces through having its own language, West Frisian, which is also spoken in a minor part of the province of Groningen, to the east. Closely related languages, East Frisian ("Seeltersk", which is different from "East Frisian (Ostfriesisch)", a collection of Low German dialects of East Frisia) and North Frisian, are spoken in the Saterland and in North Friesland areas in Germany, respectively. Friesland was a part of the German empire until 1680 when it separated and joined the Netherlands. Part of Friesland is still considered part of Germany (Ostfriesland)
Statue of Pier Gerlofs Donia, the last "King of all Frisians" known for his legendary strength and size and invention of a famous shibboleth
The English language is also closely related to West Frisian. There is a saying about it: "As milk is to cheese, are English and Fries." Another version of this saying reads (in West Frisian): "Bûter, brea, en griene tsiis; wa't dat net sizze kin, is gjin oprjochte Fries", which in English reads: "Butter, bread, and green cheese, whoever can't say that is no upright Fries" (According to legend, the 16th century Frisian freedom fighter Pier Gerlofs Donia forced his captives to repeat this shibboleth to distinguish Frisians from Dutch and Low Germans). The saying plays on the sound differences between the Dutch and Frisian words for "butter, bread, and green cheese", which in Frisian are pronounced almost identically to their English counterparts (showing the original closeness between the two languages), while in Dutch ("Boter, brood, en groene kaas"), these words sound quite different.