piano chord
G♯sus4
G♯1C♯4D♯5
The third replaced by the fourth, which leans on the third it is standing in for.
Written the other way round it is A♭sus4 — the same twelve keys on a piano, a different piece of notation.
What is true of it
G♯sus4 is G♯, C♯ and D♯ — 1, 4 and 5 counted from G♯.
These are also the notes of C♯sus2/G♯ and D♭sus2/G♯. Which name is right depends on what is underneath and what came before — the notes alone do not decide.