Translation
This is the counter to the three masters of the spear, which finished with the last play. When the masters believe my spear is pushed out of the way, I turn my spear back and strike with the butt, which has a good iron tip. The plays of these masters give me little trouble.
Interpretation
Having made a thrust at your opponent, they have stepped offline, sweeping your spear point to the side. They are attempting to counter your attack with a stab to the face as shown by the scholar of the first 3 masters.
As your spear head is carried to the right, add to its momentum and drive the butt of your spear up through the centreline. Slide you right foot back to get the distancing correct. As you do this, slide you right hand up to the near the spear head, and swing your hand to your right shoulder.
Step through with your left foot. Slide your left hand to the middle of the spear shaft. This will leave you with around a metre of spear shaft extending past your left hand to counter with. Use the anchoring of your front foot against the ground to drive the upward snap of your left hand needed to knock your opponents spear over your right shoulder. Use the pivoting of you hips to then push the spear butt into your opponents face. This should all be done as a single movement and ends in the moment shown in the picture.
It is worth noting that in the picture, the counter master has turned their right hand so that both thumbs face toward the centre. This gives a slightly slower movement than described above and also disengages the spear from your core. Such a grip means that functionally, neither end of the spear is the head. It tends to more defensive movements.