It appears that business value is not so abstract term. It is a real thing with defined examples.
EdiWiki.net and KievPress.info have publications about managing and adding business value for project managers, product managers and even for high-level organization stakeholders.
Read the article: Adding business value in organizational project management and product development practices.
Now it all makes sense.
This was an absurd topic in the university but with this explanation, we all need to pay attention to business processes and valuable work.
Thanks guys from BVOP, EduWiki and everyone else involved in this knowledge sharing.