Those looking for a beginner's guide to get started with the Fallout 76 should have a look at our Fallout 76 guide.
This Fallout 76 perk cards guide will have more on exactly how to obtain them and what you need to do to upgrade them, along with the full list of all the perk cards and their subsequent effects by rank.
There are a ton of these in the game, some requiring an increase in rank to get more out of them. Instead of choosing one permanent skill at every level, you get perk cards that can be equipped at any time, upgraded to increase their effectiveness, and even shared with your buddies at any point provided you have the Charisma. One of the more drastic changes in Fallout 76 is in it's revamp of how perks work.