Game concept
Focus
The game also links it as Focuses.
From the game's encyclopedia
Each Lifestyle contains a number Focuses, one of which must be chosen upon selecting the Lifestyle.
Focuses provide passive bonuses and influence the types of events that appear. (E.g., having the Temptation Focus will boost Fertility and increase the chances of Seduction-themed events appearing.)
Characters can switch between Focuses within the same Lifestyle without losing the ability to gain experience in that Lifestyle.
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.
Focus is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Each Lifestyle contains a number Focuses, one of which must be chosen upon selecting the Lifestyle." It covers Martial Lifestyle, Intrigue Lifestyle, Diplomacy Lifestyle, Stewardship Lifestyle, Learning Lifestyle and 1 more. The game also links it as Focuses. 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.