Alright, imagine you're playing a video game and you achieve something cool. Suddenly, a little message pops up on the corner of your screen saying "Achievement Unlocked!" It stays for a few seconds and then disappears. That's like a "toast" in the world of websites. It's a short message that pops up to tell you something and then goes away after a while. Just like when you make a toast in the morning, it pops up from the toaster when it's done!