What does Exodus 6:17 mean?

Gershon was the oldest of Levi's three sons (Exodus 6:16). He had two sons, Libni and Shimei, who became clans in Israel. This expands on what was offered about Gershon in Genesis 46. In the first count of the Jews in the wilderness, the number of Gershonite men ages 30—50 who could serve in priestly duty was 2,630 (Numbers 4:38–40). This made this group the smallest of the three clans of Levi at the time of this first count.

Moses and Aaron did not de-scend from Gershon, but from his younger brother Kohath. The context here simply notes Gershon as the oldest son and therefore the first son described following Levi. This family line is also noted elsewhere, including Numbers 3:18; 3:21; and 1 Chronicles 6:17. The Gershonites would later camp behind the tabernacle on the west side (Numbers 3:23). Their guard du-ties involved the tabernacle coverings, curtains, and screens (Numbers 3:25). Their full priestly duties are listed in Numbers 4:21–28).