In this chapter, God promises that David's son will build the LORD's temple.
The content of this chapter is very similar to 2 Samuel 7 with very little modification, so I won't have much to add here beyond what's covered in my commentary on that chapter.
David sets out to honor God, saying that while he lived in a palace, God still lived in a tent. He wanted to build a house for God so that the LORD's presence could have a permanent home in Jerusalem. God's response is that while David will not build a house (temple) for his presence, God will build a house (dynasty) for David. This is in the original source text from the book of Samuel.
The reference to the exodus (verse 21) is also in the original Samuel source text, but it takes on a new meaning in the post-exilic context of Chronicles. The references to the temple and the promise of David's everlasting dynasty also take on new meaning to the returning exiles when the book of Chronicles was written, which is why the Chronicler spends so much time on these themes.
There's only one minor deviation between the text here and in 2 Samuel, which is that Chronicles removes the references to Solomon doing wrong and being punished (2 Samuel 7:14) as well as the reference to Saul. The removal of Saul is consistent with the narrative in this book in general, which discounts the relevance of Saul and Israel's earlier disobedience. Removing the reference to Solomon's punishment is consistent with the somewhat idealized conception of Solomon that is presented in this book.
For the most part, though, this chapter is about establishing the context for the future temple in Jerusalem. The temple is central to the narrative in Chronicles, far more so than in Samuel, so this chapter is an integral part of the story.
In the next chapter, David defeats all his enemies, establishes peace throughout his land, and permits him to spend the second half of his life preparing for the temple.