Game concept
Speed
From the game's encyclopedia
Having a high Speed while Traveling will enable you to get to your destination faster. Your Speed is affected by your Skills as well as those of your Caravan Master.
A character's contribution can never be lower than 0.
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.
Speed is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Having a high Speed while Traveling will enable you to get to your destination faster." It is part of Travel. Patch 1.20.1.2, from game/common/game_concepts/04_ep2_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/04_ep2_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.