Visualization styles are configuration entities that store a reference to a drawer plugin (its Id) and a set of configuration defaults. These styles are used to create drawings. As VisualN defines it, a drawing is a ready, self-contained piece of markup (or render array) with possibly styles and scripts attached. Almost anything can be a drawing: a chart, an image gallery or even a web app.
In a sense, they are similar to image styles which are applied to an original image in order to get a styled one. In the case of visualization styles, they are applied to sets of data to get a drawing as a result. Though some drawers don't even need data to create a drawing.
Visualization styles can be created either using Available drawers preview UI or directly using VisualN > Visualization Styles administration page. Once created, they can be used anywhere on the site to create drawings: views, fields, blocks, embedded into content via ckeditor, tokens etc. Multiple styles can be created for the same drawer.
On the screenshot below a style is created for the Linechart Basic drawer provided with VisualN module.
To create a visualization style, its label must be set and drawer plugin selected. If selected drawer plugin configuration form provides required fields, those must be set up too.