No need for apologies. Battery hens are those that supply eating eggs. They are generally cramped so tightly in cages together they can hardly move. To prevent them from pecking each other - they remove most of their beaks. The chicken lives and dies there and often the body goes unnoticed for quite a spell.
We are talking thousands, maybe millions raised in what I would call egg warehouses. They never see the light of day or know what grass is. Sometimes chickens at the end of their productive period are allowed to be adopted out.
Many wonderful people adopt them to rescue them and let them live out the rest of their life - enjoying green grass, bugs and insects, sun, wind and room to stretch wings.