Translation
This scholar can not effectively injure the player so he wants to grapple in this way. That is, the scholar puts his sword inside the players right hand. Here you see the scholar enter with his sword to slide his left arm under the right arm of the player to throw him to the ground, or to put him in the lower bind, that is the strong key.
Interpretation
You cannot find an opening in your opponents armour, so using your sword as a cutting or stabbing weapon in this moment is a waste of time and effort. It still, however, makes an excellent tool.
Defend against your opponent using the master play. As your opponent pulls back with their left hand, follow their movement. There is a rocking like sensation as you absorb your opponents initial movement and then follow it back toward them.
At the end of your forward movement, slide the sword point between their right hand and hip, as shown in the picture. You are inserting the point, rather than making an attack. The mechanics will be better if you are closer than depicted, so as not to over extend your arms.
Fiore gives us two options to proceed. Which one you choose depends on your opponents reaction.
If they try to step back with their left foot, follow it with your right. Put the cross bars of your sword over their left shoulder. Anchor your left hand to your left hip and push with your right hip and hand. This will throw your opponent backwards to your left. At the very least, it will tear the sword from their grasp and leave them stumbling to catch their balance. Use all your speed to push home this advantage.
If your opponent pushes forward against you, make a shuffle step to bring your right foot closer and move your left foot next to your opponents right. Using the sword as a guiding rod, slide your left arm behind your opponents right shoulder. Pivot on your left foot, arcing your right foot behind you, so putting your opponent into the lower bind.
You will also see variants of the lower bind in the following plays.