The Chala Kazak are a group of Kazaks who live in Kyrgyzstan and now consider themselves to be Kyrgyz. However, they do not belong to any of the three main Kirgiz tribes.
The word Shala Kazak has a second meaning in Kazakhstan. It means part of the Kazak society who don't know their native language well or don't know it at all - the Qazaq language.
The actual translation for "shala" or "chala" is half. Thus, the whole meaning is "half Kazak", i.e. the person who does not know and does not like his/her native language. The word is considered to be derogatory, shameful term for Kazaks.
There is a main reason that so many Kazak people don't know and, sometimes, hate their native language - due to the heavy mass Russification of all non-Slavic nations and minorities in the Soviet Union, many Kazaks forgot their language. Shala Kazaks still constitute a big proportion of all Kazaks in the contemporary Kazakhstan Community.