V2.0 means that the text conforms to version 2.0 syntax. UTF8 stands for Universal Character Set Transformation Format, 8-bit. Next, you have comments. They are simply notes to you. Following comments are nodes.
Nodes describe shapes, light, sounds, etc.
Within the nodes are fields and values. Fields describe node attributes. Fields are optional and given in any order and values are attribute values. In order to bring life to a VRML world shapes are used. Shapes are the building blocks of a VRML world.