Why does stockfish reccomend the move?

Hi - i was analyzing a game i just played as black and i notice the engine recommend a move 19. Nd2+ to replace the mistake i made. Can somebody explain the purpose of that move and why the engine thinks its strong, it seemed a little redundant to me since there was no fork, wasn't sure exactly how to play that position.

It does not matter, both moves are winning. Your move was just as good.

You played well. This is an aggressive way to play the CaroKann.

@WiseWizardJPP ad2+ kg2 or kg1is loing work qg5+
ke1 Bh6 black idea is Qc5 or Qh4

@WiseWizardJPP Stockfish believes that the knight on d2 is more stable than on f3. For example: 19. ... Nd2 + 20. Kg1 Bh6, and if 21. f4, then 21. ... Ne4! with a huge advantage black .
@paranoyaksabunu Black's main idea in this variation is the offensive of the e6-e5-e4 pawn.