Text Visualization is a type of Data Visualization. Text visualization uses algorithms to create visual data about the chosen corpus. This includes word clouds, graphs, and many other visual resources.
There are many "off the shelf" tools that are available for free to use. Text visualization is a tool used to distantly read many sources and can reveal trends that can be used when closely reading texts.
This can't be used to read a book or to substitute reading for a course BUT it can be used to see many different resources at a glance. Want to compare many different resources, as in thousands of resources? This is a way to view topics, reoccurring phrases, and trends within the corpus that would not be possible by reading them all. We call this Distant Reading, because it can inform your research when reading a specific text.