Data visualization is a critical tool for business analysts, enabling the transformation of raw data into meaningful insights that drive decision-making. This paper explores the theoretical and practical foundations of data visualization, emphasizing its role in business analytics. We discuss key principles, cognitive theories, and visualization techniques, alongside modern tools and technologies. Additionally, we highlight the importance of data storytelling, best practices, and evaluation methods to assess the impact of visualizations. Emerging trends such as AI-driven visualization and immersive analytics are also explored, providing a comprehensive outlook on the future of data visualization for business analysts.