In my understanding a professional portfolio is a document that you give to your potential client, for example if you're an artist your portfolio is just a set of your paintings, if you're a programmer it can be your CV and screenshots of your websites.
That's how I understood and made it. But probably it depends on the embassy.
The ask:thailand community, consisting of multiple Q/A groups with over 100,000 members, powers this platform. It is not an official government resource. Our members actively contribute to this resource, and while we strive for accuracy, we cannot guarantee its complete reliability. Assistance to travelers is provided as a community service.