ArcGIS Pro is the latest professional desktop GIS application from Esri. With ArcGIS Pro, you can explore, visualize, and analyze data; create 2D maps and 3D scenes; and share your work to your ArcGIS Online or ArcGIS Enterprise portal. Read More>>
In ArcGIS Pro, your work is typically organized in a project. This means all your maps, layouts, tools and geodatabase are kept in one place. By default, a project is stored in its own system folder. Project files have the extension .aprx. A project also has its own geodatabase (a file with the extension .gdb) and its own toolbox (a file with the extension .tbx).
ArcGIS Pro user interface
For more information on each elements follow the link on ESRI page.