This is a good description of the default 40% layout and function layers on MiniVan keyboards: https://drop.com/talk/115/where-did-all-my-keys-go-a-look-in...

Of course you can reconfigure everything to suit your needs and flash directly to your board using open source QMK firmware: https://docs.qmk.fm

Custom keyboards are a great hobby for people who want to control and hack their own hardware.