The significance of using wireframes in product design lies in their ability to visualize the layout and functionality of an application or website at an early stage. Wireframes serve as a blueprint, allowing designers and stakeholders to collaborate effectively, providing a clear representation of design elements and user interactions. They help identify usability issues and clarify requirements prior to development, saving time and resources. By using wireframes, teams can iterate quickly on design concepts and gather feedback from users, ultimately leading to a more user-centered final product.