Why is this a brilliant move?
I think its because the rooks are less valuable than the queen so sacking one of them is not such a big deal unlike it would be if you were to sack the queen. Keep playing and you will understand more of these types of moves!!
It would have been better to use some brainpower, because what you wrote is nonsense. There is no mate. Not even a shadow of a mate. A draw is pretty much the best thing white can hope for.
"Brilliant move" on chess.com means "a sacrifice that's good". It isn't necessarily the best move.
In this case, Rf2 is clearly a sacrifice. It is clearly good, as after Rxf2 white has perpetual check and a draw with Qd8+ and Qg5+.
I cannot understand why this is a brilliant move? Why is checking with my queen not better?