1. What does it mean?
포카 shortens 포토카드. In K-pop conversations it usually refers to collectible photo cards included with releases or distributed through events and other offers.
Also written or said as 포토카드, photocard, poka
2. The nuance
Some are official merchandise and others are fan-made. The word alone does not establish authenticity, rarity, price, or permission to reproduce an image. Check the specific item rather than assuming all 포카 are album inclusions.
3. Examples
“포카가 구겨지지 않게 투명 케이스에 넣었어.”
I put the photocard in a clear case so it wouldn't get bent.
“친구랑 서로 없는 포카를 한 장씩 바꿨어.”
My friend and I traded one photocard each for cards we didn't have.
Sources
KASIODA: Korean language and K-pop guide
References support the meaning and usage. Example sentences are written for NoCapWiki.