The fight is actually the starting point to the episode, so preceding events are unclear, though at the end of the fight we are informed that it is a match-up created during one of Glynda's lessons.
The scene opens with the fight having already been underway for a bit. Cardin is standing casually with The Executioner resting on his shoulder, and Jaune is breathing heavily across from him. Cardin chuckles at Jaune's condition, prompting the latter to lift his weapon and charge.
Cardin easily dodges and swings his mace at Jaune, batting the shield away and sending Jaune tumbling to the floor. Jaune immediately gets up and engages Cardin once more, locking weapons with him.
Pressuring him, Cardin tells Jaune to surrender, and when Jaune refuses, he knees him in the abdomen. Jaune drops his sword and hits the ground in pain. Cardin raises his mace to bring down the finishing blow, when a buzzer sounds and Glynda stops the fight. Two screens in the background show meters designed to keep track of Aura, with Jaune's low enough to be red, and Cardin's at full.