Tushonka is a type of meat that comes from a cow, pig or sheep. The meat is cooked and canned in a can with some salt and water to keep it fresh for a long time. Tushonka is very popular in some countries as it's easy to store and can be eaten with other foods, like bread or potatoes.
Imagine you have a toy car and you put it in a box to keep it safe. Tushonka is like the toy car, but instead of a box, it's put in a can with salt and water to make sure it stays safe and fresh to eat. People eat it when they need to go on long trips or if they don't have access to fresh meat for a long time.