When it comes to measuring things like size, speed, and weight, adults use a lot of different units. One unit might be called inches or feet, another might be called pounds, and another might be called miles per hour. These are all different things that help us understand how big or heavy or fast something is.
In England, they use a special set of these units that are a little different from what we use in the United States. For example, instead of using inches to measure length or distance, they use something called centimeters or millimeters. And instead of using pounds to measure weight, they use something called kilograms or grams.
When you hear someone talking about "miles per hour," that's how fast something is going. In England, they use something called "miles per hour" too. But they also use another unit called "kilometers per hour," which is a different way to measure speed.
Sometimes it can be confusing to hear people talking about these different units, but they're all important ways to help us understand how the world works. And if you ever go to England or talk to someone from there, now you know a little bit more about the units they might use!