Numbers 26:48 is part of a census taken of the Israelites in the plains of Moab, just before they entered the Promised Land. The verse lists the descendants of Naphtali, one of the twelve sons of Jacob (Israel).

Here's a breakdown of what the verse means:

"The sons of Naphtali after their families..." This indicates that the following lines are going to list the descendants of Naphtali and group them according to their family lines or clans. The census is organized by tribes and then further subdivided into families/clans within each tribe.

"...of Jahzeel, the family of the Jahzeelites; of Guni, the family of the Gunites;" This gives the names of two sons of Naphtali (Jahzeel and Guni), and then states that their descendants formed separate families or clans. The suffix "-ites" is used to denote the members of that family or clan. So, the Jahzeelites are the descendants of Jahzeel, and the Gunites are the descendants of Guni.

In essence, the verse is saying that the tribe of Naphtali was divided into at least two major families or clans: the Jahzeelites (descendants of Jahzeel) and the Gunites (descendants of Guni).

The purpose of listing these families was to:

Organize the people: This allowed for efficient management of resources, military organization, and land distribution.
Establish inheritance rights: Land and other possessions were allocated based on family lineage.
Maintain tribal identity: By keeping track of families, they could preserve their heritage and distinctiveness.
Count the people: This census allowed Moses and Eleazar to count the number of fighting men in each tribe, which was important for military purposes and for determining the strength of each tribe when dividing the land.

Therefore, Numbers 26:48 is simply a record of the family structure of the tribe of Naphtali at the time of the census. It shows how the tribe was organized into smaller units based on descent from Naphtali's sons.