The phrase "bottom dock" refers to a section at the bottom of a computer screen where icons or shortcuts are placed for easy access to frequently used programs or files. Full definition
It comes in FOUR different versions: Bottom Dock, Bottom Dock with Calendar, Bottom Dock Messages, and Bottom Dock Calendar & Messages. (pocketberry.com)
But there are a bunch of little tweaks that we're rather fond of, including the toggles for Wifi, Bluetooth, GPS and mobile data in the notification pull - down, and the ability to swap out the phone, contacts and messaging icons in the bottom dock. (androidcentral.com)