Complex sentence: In the ghettos the population was separated by putting the Poles into the "Aryan Side" and the Jews into the "Jewish Side", any Pole found giving any help to a Jew was subject to the death penalty.
Split into simpler sentences: In the ghettos the population was separated by putting the non-Jews into the "Aryan Side" and the Jews into the "Jewish Side". Any non-Jew found giving any help to a Jew was subject to the death penalty.