Use it to show you accept someone’s point in an argument or discussion. That's a strong argument for recycling more; point taken.
Pro Tip 2/3
Humility
It conveys a humble admission that the other person’s comment is valid, even if you initially disagreed. Okay, point taken. I didn't see it from that angle.
Pro Tip 3/3
Debate Softener
Saying 'point taken' defuses tension by acknowledging the other's perspective. I understand your concerns; point taken. Let's find a solution.