Creating a UI with annotation in SAP CAPM involves using SAPUI5 annotations to define metadata for your user interface. You can add annotations to your project using the annotation editor in SAP Web IDE. Annotations can be used to define field labels, data types, formatting options, navigation, and search parameters. Once you have defined your annotations, you can use them to configure your UI controls. By using annotations, you can ensure consistency across your application and reduce the amount of code you need to write. Additionally, annotations are easily maintainable and can be updated without impacting the underlying application logic.