The B flat suspended second chord is a 3-note chord consisting of the notes Bb, C and F.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Bbsus2.
Chords that are a superset of Bbsus2. The chords include more notes but always Bb, C and F.
Chords that are a subset of Bbsus2. These contain less notes but all of them are included in Bbsus2.
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 Bbsus2 chord. Feel free to save or share the image as needed.