To create a component as part of a module you should
ng g module newModuleto generate a module,cd newModuleto change directory into thenewModulefolderng g component newComponentto create a component as a child of the module.
UPDATE: Angular 9
Now it doesn’t matter what folder you are in when generating the component.
ng g module NewModuleto generate a module.ng g component new-module/new-componentto create NewComponent.
Note: When the Angular CLI sees new-module/new-component, it understands and translates the case to match new-module -> NewModule and new-component -> NewComponent. It can get confusing in the beginning, so easy way is to match the names in #2 with the folder names for the module and component.