Hunger is when someone's tummy is rumbling and they feel like they really, really need some food. It's like when you haven't had lunch and it's starting to get late in the afternoon and you feel grumpy and maybe a bit dizzy or tired.
In the United Kingdom, some people don't have enough money to buy enough food to keep them healthy and full. This means that they might not be able to have three meals a day or they might have to skip meals. Sometimes they might have to choose between paying for things like rent or electricity and buying food, and they might not have enough money left over for both.
This can be really difficult for these people and can have a big impact on their health. Not having enough food can make them feel tired and grumpy, and it can also make them more likely to get sick. And if someone doesn't get enough food for a long time, it can even make them really, really sick.
There are some organizations in the UK that work to help people who are hungry. They might give out food at food banks or they might help people to learn how to cook healthy meals on a budget. But it's still a big problem for many people in the UK, and more needs to be done to make sure that everyone has enough food to eat.