piano chord
G♯maj9
G♯1B♯3D♯5F𝄪7A♯9
A major seventh with a ninth on top.
Written the other way round it is A♭maj9 — the same twelve keys on a piano, a different piece of notation.
What is true of it
G♯maj9 is G♯, B♯, D♯, F𝄪 and A♯ — 1, 3, 5, 7 and 9 counted from G♯.
F𝄪 is a double sharp, and it has to be: every letter from G♯ upwards is used once, so the 7 cannot be written any other way.
On an instrument that cannot reach all 5, the 5 and 1 go first, in that order.