CarouselView is a Xamarin Control which can contains any kind of View. This pre-release control can only be used in Xamarin Forms projects.
In the example provided by James Montemagno, on the blog of Xamarin, CarouselView is used to display images.
At this moment CarouselView is not integrated in Xamarin.Forms. To use this in your project(s), you will have to add the NuGet-Package (see example above).