piano chord
F♯9
F♯1A♯3C♯5E♭7G♯9
A dominant seventh carrying a ninth on top.
Written the other way round it is G♭9 — the same twelve keys on a piano, a different piece of notation.
What is true of it
F♯9 is F♯, A♯, C♯, E and G♯ — 1, 3, 5, b7 and 9 counted from F♯.
On an instrument that cannot reach all 5, the 5 and 1 go first, in that order.