1. What does it mean?
가챠 comes through Japanese capsule-toy vocabulary. Korean gamers use it for randomized item or character draws, and the term can also describe physical capsule toys or similar surprise purchases.
Also written or said as gachya
2. The nuance
A draw may use free or paid currency. The word itself says nothing about the odds, guarantees, or value of a prize; check those separately rather than assuming a desired result.
3. Examples
“가챠 결과가 랜덤이라 원하는 색은 안 나왔어.”
The capsule draw was random, so I didn't get the color I wanted.
“무료 가챠 한 번만 하고 오늘은 끝냈어.”
I used the one free draw and stopped for the day.
Sources
Sinjoeo Korean Slang Dictionary
References support the meaning and usage. Example sentences are written for NoCapWiki.