Game concept
Devotion
From the game's encyclopedia
Each point of Devotion a character gets increases their progress towards the next Level of Devotion. When a character gains Piety they also gain an equal amount of Devotion.
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.
Devotion is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Each point of Devotion a character gets increases their progress towards the next Level of Devotion." It is part of Piety. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.