What are "culture-specific elements (реалии) in the source text"?

These are concepts or objects expressed or described by words, phrases, or sentences in the source text (the original) which do not exist, or exist in different forms, in the culture of the translating language. For example, "political correctness", "affirmative action", "a fraternity", and "a sorority" are practices and concepts specific to contemporary American culture. Translating culture-specific elements (реалии) in a text is always a challenge.

Unit 2