Bundle

Drupal contain several entity types, such as nodes, users, taxonomy terms, and content blocks. Each of those types can have one or more subtypes, called "bundles", that contain additional fields. "Basic Page" and "Article" are two node bundles. Note that "bundle" is more of a technical developer-oriented term. You may encounter the terms "node type" and "content type" as well. They all mean and refer to the same thing.