Okay kiddo, I'll explain what an Alexandra wet fly is!
You know how grown-ups like to go fishing, right? Well, one way they catch fish is by using things called "flies". These are like little fake bugs that look a lot like the real ones that fish like to eat.
Now, an Alexandra wet fly is a very specific type of fly. It's named after a fancy lady named Alexandra who lived a long time ago. The fly is made up of different materials that are all put together in a certain way to make it look like a little bug. It has a body made of black or olive green thread, and some shiny feathers on top to make it look like wings.
The "wet" part of the name means that this type of fly is meant to be used underwater. When fishermen throw the fly into the water, it sinks down because it's heavy. Then it bobs around in the water, just like a real bug that has fallen in. This attracts fish who think they can eat it!
So, to sum up: an Alexandra wet fly is a fake bug that looks like the ones that fish like to eat. It's made of thread and feathers, and it's meant to be used underwater when fishing. Pretty cool, huh?