Translation
This master that flees is not armoured, and has a good fast horse. He repeatedly throws the point of his lance behind him to strike the player. And if he turned to the right, he could enter Posta Dente di Zenghiaro or Posta Donna la Sinistra with his lance, and beat and finish as in the first and third plays of the lance.
Explanation
You are being pursued by your opponent. Given your lack of armour, if they come within reach, you will be speared through the back. Being unarmoured and on horseback, your strategies largely revolve around speed and mobility. For this reason, you are riding your courser, a good fast horse. In this play, you use your speed and mobility to turn adversity to advantage.
The primary aim is to gain enough space so that your can turn around to face your opponent. You do so with this excellent example of offensive defence. Ride with your lance couched, and keep checking over your right shoulder to guage how close your opponent is. If they are closing in, flick your lance over your shoulder, then turn your body and extend your arm, throwing the point at your opponents face or their horses head. Assuming the lances are the same length, you will outreach them by at least an arms length.
Although this will cause you to slow down slightly, and possibly veer a little to the right, the need to defend themselves will disrupt your opponents pursuit. Keep doing this as often as is necessary. At some point, you will gain enough space to go fully on the attack.
As you judge that your pursuer has dropped sufficiently behind, expand the glance over your shoulder into a complete turn to the right. Either drop your lance point low into Posta Dente di Zenghiaro as the 1st master, or lift it into Posta Donna la sinistra as the 2nd master, depending on the circumstances in the moment.
Your opponent will be closing in fast. Beat their lance aside as described by the appropriate master play, and allow them to run onto the point of your lance.