A fishing net is exactly what it sounds like: a net that is specifically used for fishing. They can be made of various types of materials, such as nylon, silk, and even the materials of fibrous plants, like grass; basically, any type of thin, malleable material that can be easily manipulated. The material is formed into tight knots to create a larger piece of mesh-like material.
Some fishing nets are also called fish traps, for example fyke nets. Fishing nets are usually meshes formed by knotting a relatively thin thread.