User Secrets in .NET Core provide a secure way to store sensitive data outside of the project tree, making it easier to manage configuration and secrets for development teams. By using User Secrets, developers can avoid sharing sensitive data on GitHub or other public repositories, reducing security risks. The process involves adding User Secrets to the project, storing them in a JSON file outside of source control, and mapping them to C# models for type safety and testability. With User Secrets, developers can decouple their code from sensitive data, making it easier to maintain and update configuration settings across multiple projects and environments.