B♭sus2 (also written A♯sus2) is a suspended second chord made of 3 notes: B♭, C, F. It sounds open and airy, neither major nor minor, and you hear it in intros, worship songs and jangly pop, often moving back to the plain chord. It is the I chord of B♭ major and turns up in 5 other keys.
The library above opens on B♭sus2 with 14 shapes up and down the neck. Tap a shape to hear it, or play it one string at a time.