The warning means that a company or person may be exempt from marketing and direct communication, but exactly what this means varies depending on country and regulations.
❔ How does it work?
In some regions, it means the contact should be excluded from advertising and direct marketing campaigns. In other areas, it means the person or company may not be contacted at all without explicit consent.
Make sure to follow the regulations that apply in your country when handling contacts marked as "Blocked for marketing".