The C sharp minor eleventh chord is a 6-note chord consisting of the notes C#, E, G#, B, D# and F#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as C#m11.
Interactive piano diagram for the C sharp minor eleventh chord
Chords that are a subset of C#m11. These contain less notes but all of them are included in C#m11.