The B flat augmented seventh chord is a 4-note chord consisting of the notes Bb, D, F# and A.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Bbmaj7#5.
Interactive piano diagram for the B flat augmented seventh chord
Chords that are a subset of Bbmaj7#5. These contain less notes but all of them are included in Bbmaj7#5.