From the game's encyclopedia
Camel Cavalry are mounted Men-at-Arms that, similar to Light Cavalry, excel at scouting and pursuing the enemy.
They generally Counter Light Cavalry and are in turn Countered by Spearmen.
Camel Cavalry are often strong in Desert and Dryland Terrain.
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.
Camel Cavalry is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Camel Cavalry are mounted Men-at-Arms that, similar to Light Cavalry, excel at scouting and pursuing the enemy." It is part of Men-at-Arms. 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.