Okay kiddo, imagine you have a piggy bank with some money in it. Now imagine you and your family need to buy some things like food, clothes, and a place to live. If the things you need to buy cost more money than the money you have in your piggy bank, that means you don't have enough money.
The middle class squeeze is kind of like that. It's when people in the middle class - people who have enough money to get by comfortably but not enough to be very rich - feel like they don't have enough money to pay for everything they need.
Sometimes things cost more than they used to. That might be because the things themselves are more expensive, or because the amount of money people have to spend is worth less than it used to be (like inflation). Sometimes people's jobs don't pay them enough to keep up with how much things cost either.
So, when the cost of things goes up and people's incomes don't keep up, it's kind of like someone squeezing the middle class so they can't afford as much as they used to. Many people in the middle class are feeling this squeeze, and it can be really tough to make sure they have enough money to pay for everything they need.
Does that make sense, kiddo?