Hyperfocus is when you get really, really absorbed in doing something and you kind of forget everything else around you. It's like when you're playing your favorite video game or listening to your favorite song and you don't even notice when someone is talking to you or when it's time to do something else.
Sometimes, when people have something that they really enjoy doing, they can get hyperfocused on it. That means they might forget to eat, drink, or take breaks because they're so focused on what they're doing. It can be a good thing if you're really passionate about something and want to do your best, but it can also be a bad thing if you forget to take care of yourself or if you have other important things to do.
So, it's like when you're playing with your favorite toy and time just seems to fly by, and you don't even notice when your parents say it's time to eat or go to bed. That's what hyperfocus feels like for some people.