Fancy Bear is a group of people who are known to hack into computer systems and steal information. They are like the bad guys in a spy movie who sneak into a secret building and take important papers. Only with Fancy Bear, they do it through the internet instead of in person.
They have been around for a while and are said to be from Russia. They are believed to be a part of the Russian government and have been accused of trying to influence elections and spy on other countries. They are very sneaky and can use things like email to trick people into giving them access to their computer systems.
Fancy Bear is a pretty serious group, like a gang of internet spies, and they can cause a lot of problems. It's important to always be cautious of anyone asking for your personal information or trying to get access to your computer.