The B flat fifth chord is a 2-note chord consisting of the notes Bb and F.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Bb5.
Chords that are a superset of Bb5. The chords include more notes but always Bb and F.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the Bb5 chord. Feel free to save or share the image as needed.