piano chord
F♯sus4
F♯1B4C♯5
The third replaced by the fourth, which leans on the third it is standing in for.
Written the other way round it is G♭sus4 — the same twelve keys on a piano, a different piece of notation.
What is true of it
F♯sus4 is F♯, B and C♯ — 1, 4 and 5 counted from F♯.
These are also the notes of Bsus2/F♯. Which name is right depends on what is underneath and what came before — the notes alone do not decide.