How do I export data in excel ?

You can create submission reports in excel, CSV, PDF and the likes, and download them, here's a guide that you can refer to: https://www.jotform.com/help/326-How-To-Create-Form-Reports-in-JotForm 

You can also check it in your submissions page, you'll see the download button for excel, CSV and PDF there. Here's a guide for that: https://www.jotform.com/help/269-How-to-view-Submissions 

I also strongly suggest integrating Google Spreadsheet to your form, that will allow you to have the submission data directly stored in your online spreadsheet. Giving you a real-time list of submissions. Here's a guide on how to integrate JotForm to your Google Spreadsheet: https://www.jotform.com/help/228-How-to-Integrate-Form-with-Google-Spreadsheet 

Let us know if you need more help on this.