Fishnet is a kind of fabric that looks like a fisherman's net. The fabric has lots of small holes in it that are all connected together. You can imagine that the holes are like the spaces between the string in a real fishing net.
People often use fishnet to make clothes or accessories, like stockings or gloves. When you wear fishnet clothes, your skin shows through the little holes in the fabric. This can make the clothes look very cool and stylish!
Fishnet is also used in some kinds of fishing. If you go fishing in the ocean, you might see a big net spread out in the water. This is called a fishnet, and it's used to catch lots of fish all at once. The fish swim into the holes in the net and get trapped. Then fishermen can pull the net up and collect all the fish they caught!
So, fishnet is a type of fabric with lots of little holes in it, used to make cool clothes and also to catch fish.