What is WoTLK client to version 3.2.0

Each update in World of Warcraft, be it an expansion or a patch, is designated with a number. The first number is the expansion, the second one the patch number. The third number denotes whether it is a minor patch. Your installed version of the game needs to match the version running on the server, or you cannot play the game.

For example:

Patch 1.0 was classic World of Warcraft
Patch 2.0 was The Burning Crusade
Patch 3.0 was Wrath of the Lich King.

Patch 3.2.0 noted in the question was the patch in which the Argent Tournament was added in Icecrown.
Icecrown Citadel was added in Patch 3.3, and the current client is 3.3.3.