1. What does it mean?
버프 means buff. It can be an in-game effect that improves a character temporarily, or a balance adjustment that permanently strengthens an ability or item until another change. Outside games it can jokingly mean a helpful boost.
Also written or said as beopeu
2. The nuance
Read the context: receiving a temporary speed effect and being improved in a patch are different senses. A harmful status effect is a 디버프; a balance reduction is a 너프.
3. Examples
“이 버프가 끝나기 전에 이동하자.”
Let's move before this buff expires.
“이번 패치에서 방어력이 버프됐어.”
The defense stat was buffed in this patch.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.