Cost of living is how much money you need to have to pay for all the things you need every day. This includes things like food, a place to live, clothes, and things like electricity, water, and gas.
Think of your lunch money. You need to have a certain amount of money every day to pay for your lunch. But imagine if you needed to have more money to be able to pay for everything else you need or want to do. This is what adults have to think about when they have to pay for all the things they need and want every day.
Some places are more expensive than others. For example, if you live in a big city, things might be more expensive because there are more people living in the same area, which makes everything more expensive. If you live in a small town, things might be cheaper because there are fewer people living there and fewer things to buy.
In summary, cost of living is like having a big piggy bank that you need to fill with money every day to be able to pay for all the things you need and want. Some places are more expensive than others, and you need to be prepared to adjust the amount of money you need to have depending on where you live or visit.