Package Specification and Package Body refer to the definition body and implementation, similar to the .h and .cpp files in C , this package is the implementation of the class (Class).
Task is usually for an executive, which has a standalone thread or process.
For a simple example, you have written a simple executable, which is to use some class a, at which time the executor can be defined as task, the definition of class A is used with package specification, and implemented using package body.
