A strong exchange sacrifice to get a better endgame!
After a sharp gambit in Slav defense white has a strong kingside attack. Black decides to give an exchange ( rook for minor piece) to stop the white initiative and go for a better endgame.-
Why a better endgame? Because the pair of bishops and the d-pawn would bring white surely under pressure.
Here our starting position:
Normally black players would try here to save here the rook with 1. ...Rf8 and give the bishop back with 2. exd6. But this would not stop the white initiative. It would presumely go on with 2. ...Nd7 3. Nf3 and Bxh6 and a strong kingside attack.
So black decided to give the exchange to stop the kingside initiative and to go for a better endgame
White took the rook and may have felt well for a moment. But then black started a very successful 2-step plan
A) Exchanging the queens
B) Winning the endgame
Here more about exchange sacrifice:
And about passed pawns: