All-purpose little pat on the back meaning good job, cheers, or fair play. Say it when your mate sorts you out, nails a task, or does you a solid. The fun bit is it also doubles as top-tier sarcasm. Same two words, totally different vibe, depending on the tone, the pause, and the weaponised eye roll.
"I’ve bagged us tickets for the match, mate. Nice one, you absolute legend. Turns out they’re restricted view though, we’re behind a pillar. NICE ONE, cheers, brilliant"