piano chord
A♭sus4
A♭1D♭4E♭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
A♭sus4 is A♭, D♭ and E♭ — 1, 4 and 5 counted from A♭.
These are also the notes of D♭sus2/A♭ and C♯sus2/A♭. Which name is right depends on what is underneath and what came before — the notes alone do not decide.