From the game's encyclopedia
An activity where the Liege travel to a County in the Realm to oversee the local magnates and nobles.
They will have opportunities in one of the following focus areas:
• 
Claims & 
Offer Vassalization Acceptance
• 
Taxes, 
Development, & 
Control
• 
Levies, 
Opinion, & 
Popular Opinion
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.
Inspection is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "An activity where the Liege travel to a County in the Realm to oversee the local magnates and nobles." It is part of Activity. The game also links it as Inspections. Patch 1.20.1.2, from game/common/game_concepts/01_bp3_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/01_bp3_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.