This article explores the nature, classification, and functional role of phraseological units in modern language use. Phraseological units, also known as idioms or set expressions, represent a significant aspect of linguistic richness and cultural identity. The study outlines the main types of phraseological units, their structural and semantic characteristics, as well as their pragmatic functions in communication. Special attention is given to the translation and interpretation challenges they pose across languages. The analysis is supported by examples from English and other languages to highlight cross-cultural nuances. This research contributes to a deeper understanding of phraseology as a vital component of linguistic competence and intercultural communication.