@Configuration: Spring’s annotation to flag this class as a collection of bean definitions, needed to autoconfigure our application

@Bean: Spring’s annotation to turn this method into a Spring bean, added to the application context

CommandLineRunner: Spring Boot’s functional interface for an object that is automatically executed once the application is started

R2dbcEntityTemplate: Inject a copy of this Spring Data R2DBC bean so we can load a little test data

args -> {}: A Java 8 lambda function that is coerced into CommandLineRunner