What does Nehemiah 1:2 mean?

These are the words of Nehemiah, son of Hacaliah. In the month of Kislev, during the twentieth year of King Artaxerxes, I was in the fortress city of Susa. Nehemiah 1:2 - Modern Text Bible

(Nehemiah introduces himself and sets the scene: he’s in Persia, serving the king, during the winter month of Kislev.)