NLU is used in natural language processing (NLP) tasks like topic classification, language detection, and sentiment analysis. For instance, you may ask Siri or Alexa, "what's the weather today?" NLU will recognize your concern (in this case, this is the weather).
Chatbot development relies heavily on natural language processing (NLP). Thus, this ability to understand the context, syntax, and intent gradually leads to chatbot development and breakthroughs.