The default base map is composed of 4 layers, plus a style.
Giraffe projects start with a few layers by default:
Default - a blank drawing layer
Basemap Group
Map labels - Street names, cities, and regions from Mapbox
3D buildings - 3D white building massing from Open Street Map
POI Labels - Points of interest like restaurants, retail, and community hubs
Transit Labels - Transit stops
Landmark Buildings - Beautifully modeled, architecturally significant buildings, provided by Mapbox
Trees - 3D trees that approximate real-life conditions by Mapbox
Satellite - Global Satellite imagery From Mapbox
You can adjust the visibility of the layers within the base map group the slightly change the visual style of the map (like turning off street names, for instance).
Note: Your project may have different layers if you did not use a Giraffe template, or you removed one or more layers.
If your project is missing the Base map layers, search the Layer Library for "base map" to re-add them!