The A/SF-01 B-wing starfighter, also designated as the A/SF-01 B-wing assault starfighter, more commonly referred to as the B-wing, was a heavily armed Rebel Alliance single-pilot starfighter and bomber manufactured by Slayn & Korpil. The B-wing saw action during the Galactic Civil War and was subsequently substituted by the B-wing Mark II.
Do you know why the B-Wing is called the B-Wing? It doesn’t look much like a B. During production for Return of the Jedi, two new Rebel fighters were created and simply labeled A fighter and B fighter. Visual effects artist Bill George had a lot of input on the B fighter, and it received the nickname the Bill-wing. Star Wars Legends eventually called the ship the Blade-wing for its swordlike appearance in attack mode. The Star Wars Rebels episode Wings of the Masters brought the name into canon. So we can assume the B stands for Blade.