piano chord
C♯maj7
C♯1E♯3G♯5B♯7
Major triad with a major seventh: a half step below the root, an octave up.
Written the other way round it is D♭maj7 — the same twelve keys on a piano, a different piece of notation.
What is true of it
C♯maj7 is C♯, E♯, G♯ and B♯ — 1, 3, 5 and 7 counted from C♯.
On an instrument that cannot reach all 4, the 5 goes first, in that order.