What is the meaning of Daniel 9:2?

* The two F.O.G. Bibles & Commentary below are currently a work in progress.

in the first year of his reign, I, Daniel, understood from the sacred books, according to the word of the LORD to Jeremiah the prophet, that the desolation of Jerusalem would last seventy years.

Berean Standard Bible (BSB)

in the first year of his reign I, Daniel, understood by the books the number of the years about which the word of Yahweh came to Jeremiah the prophet, for the accomplishing of the desolations of Jerusalem, even seventy years.

World English Bible (WEB)

In the first{H259} year{H8141} of his reign{H4427}{(H8800)} I Daniel{H1840} understood{H995}{(H8804)} by books{H5612} the number{H4557} of the years{H8141}, whereof the word{H1697} of the LORD{H3068} came to Jeremiah{H3414} the prophet{H5030}, that he would accomplish{H4390}{(H8763)} seventy{H7657} years{H8141} in the desolations{H2723} of Jerusalem{H3389}.

Strong's King James

In the first year of his reign, I, Dani'el paid attention in the writings for the number of years for the completing of the ruins of Yerushalayim, which were the word of יהוה (Yahweh) to Yirmeyah, the prophet. 70 years!

The F.O.G*

The F.O.G Paraphrase

in the first year of his reign, I, Daniel, have understood by books the number of the years, (in that a word of Jehovah hath been unto Jeremiah the prophet,) concerning the fulfilling of the wastes of Jerusalem—seventy years;

Young's Literal Translation