Okay, imagine you're playing pretend with your friends, and one friend says they're a princess from a magical land. But then another friend comes along and says they're the same princess but with a different name. That's kind of like what website spoofing is, but with websites on the internet.
When you go to a website, you type in the web address, like www.google.com or www.youtube.com, and that takes you to the real website. But sometimes people make fake websites that look just like the real ones, but they have a different web address that's similar or spelled differently.
They do this to trick people into thinking they're on the real website, and then they might ask you for your password or credit card information. But if you enter that information on the fake website, the bad guys can use it to steal from you.
So it's important to always check the web address at the top of the screen to make sure you're on the real website, and not a fake one. And if you're not sure, ask a grown-up for help.