Genesis 36 is a genealogical chapter, listing the descendants of Esau (also known as Edom). Verse 23, "These are the children of Shobal: Alvan, Manahath, Ebal, Shepho, and Onam," is simply stating that Shobal, one of Esau's descendants, had these five sons: Alvan, Manahath, Ebal, Shepho, and Onam.

Essentially, it's a line in a family tree. It establishes that these five individuals were part of the Edomite lineage and were the direct offspring of Shobal.

Significance (in context):

Tracing the Edomite Lineage: The entire chapter is dedicated to tracing the lineage of Esau, who was Jacob's twin brother. This is important because the Israelites and Edomites had a complex relationship throughout the Old Testament. Understanding their ancestry helps to understand their relationship.
Establishing Tribal Connections: The names listed often represent clans or tribes that later emerged from this lineage. While we don't know much about these specific individuals, the verse indicates the beginnings of larger familial and tribal groups.
Historical Record: Although seemingly simple, these lists were important historical records for the Israelites. They documented family relationships, land ownership, and social structures.

In short, the verse is a straightforward statement of Shobal's sons, contributing to the broader genealogical record of the Edomite people.