It actually is a bit more simple than that - The Bishop is sacrificing itself to force the Queen away and then the c2 pawn promotes into a new Queen 
One line is: 22...Bd4!! 23. Qc1 Be3! and any Queen move is met by ...c1=Q such as
23...Be3! 24. Qxe3 c1=Q 25. Qxc1 Qxc1 or
23...Be3! 24. Qe1 c1=Q 25. Qxc1 Qxc1
I made my first brilliant move... but i don't understand! It just looked like I hung my bishop, but it said brilliant. I am so upset that i blundered and completely missed the next line, and i lost the game
i just got to 900 daily rating too
(edit) i am aware that if the queen captures the pawn promotes but after 23. Qc1 it said Bb5 was a blunder and Be3 was best! It looks like Be3 would just be pointless because the queen could move away