Aharon's passing is recorded together with the elevation of the Levites to ministers to Hashem. Moshe points out that the 70 souls who went down into Egypt have now become like the stars of the heaven in abundance. One of the most recognizable features of a Jewish home is the lighting of candles in honor of Shabbos. The above verse is the source of this concept. Ostensibly, it's hard to see the link between the manna, the miraculous food that the Jewish People ate manna in the desert, and the lighting of Shabbos candles.
Man is a relative animal.
Our perceptions operate in terms of contrast. We understand what day is because every evening the sky darkens and becomes black. If there were no night, not only would we have no concept of night, we would also have no concept of day. When the Children of Israel were in the desert, G-d fed them a miraculous food called man. The man could taste like any food, and yet Bnei Yisrael grew tired of it and complained to Moshe that it was tasteless.