What does Nehemiah 12:33 mean?

The priests and the Levites purified themselves; and they purified the people, and the gates, and the wall.

Then I brought up the princes of Judah on the wall, and appointed two great companies who gave thanks and went in procession. One went on the right hand on the wall toward the dung gate;

and after them went Hoshaiah, with half of the princes of Judah,

Judah, Benjamin, Shemaiah, Jeremiah,

and some of the priests’ sons with trumpets: Zechariah the son of Jonathan, the son of Shemaiah, the son of Mattaniah, the son of Micaiah, the son of Zaccur, the son of Asaph;

and his brothers, Shemaiah, Azarel, Milalai, Gilalai, Maai, Nethanel, Judah, and Hanani, with the musical instruments of David the man of God; and Ezra the scribe was before them.