Complex sentence: NLP asserts that amongst the many possible submodalities, there will often be a handful of so-called "critical" submodalities which can functionally effect large-scale change, and that they differ between people, and can be identified by observation and inquiry.
Split into simpler sentences: NLP asserts that amongst the many possible submodalities, there will often be a handful of "" critical "submodalities" capable of effecting large-scale change. These differ between people, and can be identified by observation and inquiry.