From the game's encyclopedia
Meritocratic is a Bureaucratic Government Form similar to Celestial, in which the Liege appoints characters as Governors, of which there are two types, Civil and Military.
Characters have access to Influence, Noble Families, and Family Mansions.
Independent Rulers have Legitimacy, while Vassals focus on obtaining Merit.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Meritocratic is an entry of Crusader Kings III's in-game encyclopedia (All Under Heaven). The game explains it: "Meritocratic is a Bureaucratic Government Form similar to Celestial, in which the Liege appoints characters as Governors, of which there are two types, Civil and Military." It is part of administrative_government. Patch 1.20.1.2, from game/common/game_concepts/tgp_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/tgp_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.