Game concept · All Under Heaven
Military Governor
The game also links it as Military Governors, Military.
From the game's encyclopedia
A Military Governor is a Governor with military Subject Obligations. They are able to field Title Men-at-Arms, unlike Civilian Governors, and will use them to protect the Realm from foreign incursions and support other Governors in need of military aid.
Characters who pursue a Military Career Path can become Military Governors.
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.
Military Governor is an entry of Crusader Kings III's in-game encyclopedia (All Under Heaven). The game explains it: "A Military Governor is a Governor with military Subject Obligations." It is part of Governor. The game also links it as Military Governors and Military. 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.