Complex sentence: Shalom Aleichem is a traditional song sung Friday night at the beginning of Shabbat, the Jewish Sabbath, welcoming the angels who accompany a person home on the eve of the Sabbath.
Split into simpler sentences: Shalom Aleichem is a traditional song sung Friday night at the beginning of Shabbat, the Jewish Sabbath. In this case the words are used to welcome in the angels who accompany a person home on the eve of the Sabbath.