Suppose I have a question and answer plugin. And I have my user data (questions and answers) within it. Now suppose I want to transfer those data to a new wp plugin or a theme. How do I do that ?
Data should be stored on the DB, so your plugin should be saving all those QA on a table, so should be able to export that table and then you will have to know how the new plugin storages its data (which table and how) and you import there.