The next line tells us we will be defining a shape node VRML is all about nodes. This tells us we are starting a structure. We end it later. The indentation is fairly standard. Now look at the geometry line.
Nodes have fields, which are just places to put stuff.
Field names usually begin with a lowercase letter, and node names begin with an uppercase letter. Much of vrml consists of the name of a field followed by its contents. In this case, we are telling the shape what kind of geometry to use. The contents of the geometry field will be one of a number of special nodes designed to fit here. Each of these geometry nodes has its own fields.