Puzzle

Could someone please explain this puzzle to me? I thought the idea was to use the skewer on the queen/rook with the bishop to gain a rook, but the puzzle ends up taking a bishop but losing the rook (queen would take after last move). How does this help black?

en.lichess.org/training/55844

Black takes the bishop for free. Rxe3. White cannot capture Qxe3 because Bd4 skewers queen to king.

Hi guys,
Could you explain someone on training game 47558 why is the best move Re3-e8?
Thanks

Beginner1975, isn't it obvious? Black is lucky he has a move which both defends by blocking check, then discover attack check, Re8+.

Black wins a rook. Rxh8.