What does 2 Chronicles 35:25 mean?

Jeremiah wrote a song of mourning for Josiah, and all the singers—men and women—still sing about Josiah in their laments to this day. These songs became a tradition in Israel and are written in the book of laments. 2 Chronicles 35:25 - Modern Text Bible

(Josiah's death was so significant that Jeremiah and others composed laments for him, which became a lasting tradition.)