From context, is a character in the Korean web novel / manhwa "I Became the Wife of the Monstrous Prince" (괴물 왕자의 신부가 되었습니다 / Became the Bride of the Monster Prince ) — also known in some Chinese translations as "Bei Fu Lu Gong Zhu" (被俘虏的公主) or similar titles.
It seems you're asking about the character (likely Sera Noel / Sera / Sarah ) and the phrase "bei fu lu gong zhu de xia luo" (被俘虏公主的下落 — the whereabouts of the captured princess ), which likely refers to a specific plot point in a Chinese-translated web novel or manhua. Sera Noel - bei fu lu gong zhu de xia luo