To make it ready to fire.
As you worded it, it means nothing.
An airsoft repeater is an airsoft gun that you have to cock to get each round in the chamber.
Cock it? I think you just shoot until it runs out.
You only have to cock it if it is a spring gun.
As you pull the trigger.
Mechanical noise
by pulling the hammer back.
You cock the BB gun without loading any BB's into it just air.
sear
'Cock it and pull it' probably refers to the sport of shooting. Cock it refers to 'cocking' a shotgun; this is loading the gun with bullets and preparing the gun to fire. Pull it refers to what is said by people as they shoot. When a shooter yells 'Pull!' the target is released, for example a clay disc (or clay pigeon) and the shooter tries to hit the flying target.
May be a hammer or a striker, depending on design of the gun.