ABP Suite generates the source code for Entity, Repository, Application Service, Code First Migration, JavaScript/TypeScript and CSHTML/HTML and necessary Interfaces as well. ABP Suite also generates the code according to the Best Practices of software development, so you don't have to worry about the generated code's quality.

Since you have the source code of the building blocks of the generated CRUD page in the correct application layers, you can easily modify the source code and inject your custom/business logic to the generated code.