Food speculation is when some people buy and sell food in a way that makes the price change. Imagine you have a cookie and your friend wants it. They offer you a dollar for it, but you think it might be worth more later, so you don't sell it. Later, another friend offers you two dollars for it. Now, you sell it and make a profit. This is kind of like what people do with food. They buy it when it's cheap and then sell it when the price goes up to make money.
However, this can cause problems for people who need the food to eat. When the price of food goes up, it can be harder for them to afford it. So, some people think that food speculation is not fair because it can hurt people who are already struggling. That is why some governments and organizations try to limit food speculation to protect people's access to food.