According to the author of the book, this verse lists some of King David's sons, telling us about their mothers and where they were born. It helps us understand the family of David and who his children were.
1 Chronicles 3:1: Now these were the sons of David, which were born unto him in Hebron; the firstborn Amnon, of Ahinoam the Jezreelitess; the second Daniel, of Abigail the Carmelitess: [Daniel: or, Chileab]
This verse lists the sons of David born in Hebron, which might have differences in names, order, or number compared to 1 Chronicles 3:1.
2 Samuel 3:2: And unto David were sons born in Hebron: and his firstborn was Amnon, of Ahinoam the Jezreelitess;