Have you ever played with a long stick or a broom? You can hold it with both your hands and push it forward to make something move away from you, right? Well, push of pike is kind of like that, but with a really long stick that soldiers used to carry in battle!
Back in the olden days, soldiers used a long stick called a pike that was taller than them. They had to hold it with two hands and stand in a line with other soldiers who also had pikes. When the enemies came close, the soldiers would push their pikes forward to make the enemies move back.
The soldiers had to be very strong and work together to push the pikes because they were really heavy and difficult to move. The pikes were also sharp at the end, so it helped keep the enemies away!
So basically, the push of pike was a battle tactic where soldiers used a long stick to push their enemies away and keep themselves safe during a battle. It was a way for them to work together and stay strong against their enemies.