Okay, so do you know what Zeus is? No, not the god of thunder. I mean the computer thingy.
So, Zeus is a piece of software that some bad people made to steal information from other people's computers. It's like a spy that sneaks into your computer and looks at all your personal stuff.
Now, do you know what a Trojan horse is? No, not a horse that's from Troy.
See, a long time ago, there was a story about a big wooden horse that some sneaky soldiers gave to the people of Troy. The horse was actually filled with soldiers, and when the people of Troy brought the horse inside their city walls, the soldiers came out and took over the city.
Well, the people who made Zeus thought they were being very clever, and they called their program a Trojan horse too. Just like the soldiers snuck into Troy, Zeus sneaks into people's computers and takes over.
But, instead of soldiers, Zeus steals your personal information like your passwords, bank account information, and other stuff you don't want other people to see.
So, you should be careful with your computer and make sure you don't download anything that looks suspicious. And if you think Zeus might be on your computer, you should ask a grown-up to help you get rid of it.