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.
You are right, I saw some blank submissions in your form. Here's a screenshot:
It is possible that some of your users or visitors did not fill up the form and just hit the submit button. It is also possible that spam bot are automatically submitting the form.
I would suggest you to insert a Captcha field in your form. Here's a guide: https://www.jotform.com/help/205-How-to-Add-a-CAPTCHA-field
You may also want to set some fields as "Required" so that the form cannot be submitted unless the required fields are filled up.
Hope that helps. If you have any questions, let us know. Thank you.