The book of Baruch is set during the time of the Babylonian invasion, the destruction of the temple and the taking of its treasures, time of capturing the king, other nobles, and people of the land, taking them into exile. The words are addressed to these exiles.
The letter encourages them with assertions that the Lord will continue to give strength and light to the people during their separation from home and temple. The letter contains words of judgment, that the people by their own actions had brought on their calamities. Yet, even though, they deserved what had happened, they may turn to the Lord for forgiveness and deliverance.
Following the prayer is a poem that praises Wisdom.
The original readers of this book could use its prayers and descriptions of wisdom to help face the difficult circumstances of their own lives. So can we.