Not a programming question, section where you ask questions about your code, and you don't show any. So I moved the topic.
TSV: tab-separated values
CSV: comma-separated values
These file formats allow to store data structured in columns separated by tabs or commas (or other like semi-colons). Data can be numbers or strings.
For more details, google for the abbreviations... And open these files in a text editor to see what they look inside.
VLW: that's a binary file format specific to Processing, holding font information in a bitmap format (at a given size). They can be created inside the PDE and loaded with loadFont().
TSV / CSV can be created with saveStrings() and loaded with loadStrings() but now Processing has a special API to ease their processing, see the Table class.
Note: the extensions ending with ~ are probably backup files created by a text editor: some of them automatically backup the current file before saving changes. A rather primitive trick, better use a good VCS (version control system).
