וּפְקוּדֵ֖י בְּנֵ֣י גֵרְשׁ֑וֹן לְמִשְׁפְּחוֹתָ֖ם וּלְבֵ֥ית אֲבֹתָֽם׃
And those that were numbered of the sons of Gershon, by their families, and by their fathers’houses,
Read kabbalistic (mystical) interpretation of Numbers 4:38: and classical mystical sources.