A box compression test is like squishing a box to see how strong it is. When we put stuff in a box and stack them up, they need to be able to hold the weight of the stuff inside and the weight of the other boxes on top of them.
To test how strong a box is, we use a machine that looks like a big press. We put the box inside the machine and then slowly push down on it until it starts to squish. The machine measures how much weight it takes to squish the box and we can use that information to see if the box can hold up under a lot of weight.
Just like how we might test how strong a toy is by seeing if it breaks when we play with it, we test boxes to make sure they won't break when they're stacked up with other boxes. This way, we can make sure that the things we put in the boxes will stay safe and won't get damaged.