What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
From what I understand, responsive form simply means the ability of the website or form to respond or easily adjust its layout, content and design depending on where it is presented, like what browser or device it is being viewed on.
You can also search for Google about it, but that's basically what responsive mean when it comes to web design.
Hope this helps. Let us know if you need further information.
Here is a blog post on the subject: What is a responsive online form?