These are the basic terminals you will see throughout the game. Repair is for item repair, items decay as they are used and need regular maintenance, but there are limited items that can not be repaired (usually marked with a (L) after item name). The trade terminals (often refered to as just TT), are where you can buy the basic weapons, armor, and tools, plus ammo and other basic items you will need. The revival terminal is where you will revive to if you are killed, you should go to the nearest one to where you died at. The society terminal is for finding and interacting with or even creating a society, I recommend finding a good one to help you get started before creating one of your own.
How to prevent being overcharged - TT stuff guide
Here is a link to a list of TT items and where to find them. Thanks to
ViagraFalls for this one, it's worth reading.