These patterns are part of the standard Object-Relational model mapping in DotNetNuke and DotNetNuke modules.

Controller is a class suffix used to declare 'doing' actions on entities. This is usually database interactions like 'add', 'delete', 'update', but might also be thing like calculating values or doing other processing. It can be thought of as a business-layer class which largely wraps the database layer.

DataProvider is a singleton pattern class which is used to define all the database - layer interactions for a given module. It's the central point for definining all the database activity for a module. Note that DataProvider is implementation agnostic in design - it doesn't specify that the data necessary will be saved by Sql Server.

SqlDataProvider is an implementation specific provider which implements all the methods of the DataProvider. In theory you could build an OracleDataProvider or a MySqlDataProvider but in practice people rarely do. The SqlDataProvider layer contains the actual Sql-specific implementation of the database calls.

Info is a class suffix denoting an entity., Typically this is the database table defined as a class, so you might have UserInfo, TabInfo and if you are creating your own module, WidgetInfo.

Note that you don't have to use any of these patterns when building a module, but best practice dictates that you follow the style of DotNetNuke modules when implementing your own modules. You could theoretically code database interaction directly into your code-behind pages if you wanted. Most people prefer to follow the patterns in the rest of DotNetNuke just so the entire codebase has the same feel.