guitar chord
A♭sus4
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.
Every fingering that fits a hand
446644
moderate · barre
466644
hard · barre
44664x
moderate · barre
4411xx
hard
xx6644
hard
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.
The easiest of the 5 fingerings below is 446644: 3 fingers, one of them barring the 4th fret, held at the 4th fret.
None of them uses an open string, so this chord moves up the neck unchanged — the same shape 1 fret higher is the chord a semitone above.
3 of the 5 need a barre.
Where its notes are on the neck
The brass dots are A♭, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
A♭sus4/D♭
x46644
A♭sus4/E♭
x6664x
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.