A machine alert is an alert that is timed by a machine, not by a human. It's pretty quick. It's also quick-witted. Machines can move and think so much faster than us, after all.

機敏 is often used to describe the way someone responds promptly to various situations, and implies being highly responsive and adaptive.

This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.