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.
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I assume that you were testing your form; but if you leave fields' spaces empty, your notification mail comes like your screenshot with variable names. I've cloned your form and tried to get notification mail. It looks like this:
To force users to fill one of your field, you need to make it "Required".
Please don't hesitate to ask, if anything stays blank.