Sure, but first a little background in case you aren't familiar (if you are, I aplogize):
In Malaysia, there are regulations that give preferential treatment to ethnic Malays. This makes Malaysia unattractive to foreign businesses and foreign investment and the article says that Malaysia has lost foreign investment because of it. Ethnic Chinese in Malaysia are opposed to it, and Najib is caught between pressure from non-Malay parties to change those regulations and his own party that does not want to.
Najib promised to undo some of these restrictions, and is facing a backlash, which means a "negative reaction" to those promises from his own party. Because of this, he may not be able to fulfill his promises and accommodate the parties that are in favor of such changes.
Does that make it any clearer?