1. What does it mean?
세계관 ordinarily means a worldview. In entertainment talk it often means the setting and lore linking characters, stories, or releases, including invented universes around music projects.
Also written or said as segyegwan
2. The nuance
That content-world sense differs from a person's philosophical outlook. Similar colors or symbols may invite theories, but do not automatically confirm that two works share official lore.
3. Examples
“마법을 쓰는 조건이 정해져 있어서 세계관이 이해하기 쉬웠어.”
The rules for using magic made the fictional world easy to understand.
“이 뮤직비디오는 앞 앨범의 세계관과 이어진대.”
They say this music video connects to the previous album's fictional universe.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.