How do we know that “the party” referred to in the opening sentence of the first paragraph has just arrived from another country, and cannot speak English?

The party celebrates the marriage of Ona Lukoszaite and Jurgis (pronounced Yoorghis) Rudkus. Though Jurgis “could take up a two-hundred-and-fifty-pound quarter of beef and carry it into a car without a stagger,” the wedding and the party leave him “frightened as a hunted animal,” and he stands nervously in a corner. The guests, all of Lithuanian heritage and ancestry, gather in the community hall with a “charming informality.”