piano chord
G♯11
G♯1B♯3D♯5F♯♭7A♯9C♯11
Six notes in theory; in practice the third is usually dropped, because the eleventh sits a half step above it.
Written the other way round it is A♭11 — the same twelve keys on a piano, a different piece of notation.
What is true of it
G♯11 is G♯, B♯, D♯, F♯, A♯ and C♯ — 1, 3, 5, b7, 9 and 11 counted from G♯.
On an instrument that cannot reach all 6, the 3, 5 and 1 go first, in that order.