former; previous; old
first move (in go, shogi, etc.); opening move
「先」 has another reading with different meanings.
point; tip; end; nozzle
先月は忙しかったなあ。
Last month was really busy.
先生のご意見はいかがですか。
What is the teacher's opinion?
先日お会いした方からお礼の手紙が届いた。
I received a thank-you letter from the person I met the other day.