Okay kiddo, so Adobe Flash is a special program that websites used a long time ago to make things move around and do cool things.
You know those videos you watch on YouTube or the games you play on your computer? Some of those used Adobe Flash to work.
But now, websites don't use Adobe Flash so much anymore because it's not very safe. Sometimes bad people could make things that looked like Adobe Flash, but when you clicked on it, it would give your computer a virus.
So now, if you see something that asks you to download Adobe Flash, you should ask a grown-up first. And if you don't need it, it's probably better not to download it at all.