A vast majority of clinical information, rich with patient-specific details and nuanced observations, resides in unstructured formats such as physician's notes, pathology reports, and medical literature. This wealth of data often remains underutilized due to the challenges of manual extraction and analysis. Natural Language Processing (NLP), a specialized field of Artificial Intelligence, offers powerful techniques to unlock this untapped potential by enabling computers to understand, interpret, and process human language. This work explores the pivotal role of NLP in transforming unstructured healthcare data into actionable clinical insights. It details key NLP tasks-including Named Entity Recognition, Relation Extraction, Text Summarization, and Question Answering-and the underlying technologies, from traditional machine learning to advanced deep learning models like Transformers. The paper examines diverse applications, such as enhancing diagnostic accuracy, personalizing treatment strategies by extracting social determinants of health and patient preferences, advancing medical research through cohort identification and pharmacovigilance, and optimizing healthcare operations via automated coding and quality reporting. Furthermore, it addresses significant challenges, including the variability of clinical text, data privacy concerns (HIPAA/GDPR), the need for large annotated datasets, algorithmic bias, and the imperative for explainable AI. Ethical considerations, particularly regarding bias mitigation and ensuring patient confidentiality, are highlighted. Finally, the paper looks toward future directions, including the impact of Large Language Models (LLMs), multimodal NLP, and