وَلَا إِلَهَ غَيْرُهُ
There is no god other than He
This statement is similar to laa ilaaha illalaah and to state Tawheed in this manner, that is, nafyi (to negate divinity of anyone else) and ithbaat (affirm it for Allah) is powerful as it clearly limits divinity to Allah alone. Ithbaat alone would be open to different intepretations.
The statement of the shaykh ‘wa laa ilaaha qayruh’ means that there is no HAQQ (true) god other than Allah. It would be wrong to say that there are no other gods because there are other objects and beings that people worship but they are all false and Allah is the only true God deserving of worship.
The fact that there are other false gods is affirmed in the Quran:
أَفَرَأَيْتَ مَنِ اتَّخَذَ إِلَـٰهَهُ هَوَاهُ
Have you seen he who has taken as his god his [own] desire [Al-Jathiya 45:23]