Hash is like when you take some pieces of food and chop them up into very, very small pieces. It's like putting the food in a blender or using a knife to cut it up really, really small.
This makes the food easier to cook and gives it a different texture than if you left the pieces bigger. It also blends different foods together, like potatoes and meat or vegetables, to make a tasty meal all mixed up together in one dish.
Some people like to eat hash for breakfast with eggs, while others enjoy it for dinner with a side of veggies. It's a yummy way to use up leftover food and turn it into something new and tasty!