From the introduction:
Every adventure has a beginning, and every adventurer does as well. They may be born into a life of adventure, or come from humble origins. Whatever the case, a PCs background can shape who they are and who they become.
"Beginnings" offers ten additional backgrounds (and four variants) for players to choose from when creating their characters. Each background comes with a brief description, a selection of starting proficiencies and equipment, a feature, and tables for choosing or randomly determining personality traits, ideals, bonds, and flawss. These backgrounds are intended to supplement the selection available in the Player's Handbook.
The backgrounds included in this supplement are: Beggar, City/Town Guard (or Caravan Guard), Commoner/Peasant, Courier, Gravedigger (or Graverobber), Healer, Miner, Road Warden (or Bounty Hunter), Shopkeeper (or Innkeeper), and Teamster/Wagoneer.