What does 2 Samuel 15:12 mean?

While he was offering sacrifices, Absalom sent for Ahithophel the Gilonite, David’s trusted advisor, from his hometown of Giloh. The conspiracy kept growing, and more and more people joined Absalom. 2 Samuel 15:12 - Modern Text Bible

(Absalom recruits key allies, including one of David’s top counselors, and his movement gains momentum.)