The B flat dominant sharp ninth chord is a 5-note chord consisting of the notes Bb, D, F, Ab and C#.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Bb7#9.
Interactive piano diagram for the B flat dominant sharp ninth chord
Chords that are a subset of Bb7#9. These contain less notes but all of them are included in Bb7#9.