I there a way to show the user which date he has selected on the date reservation widget?

I want to be able to show the user a confirmation before they hit submit.

I am not sure if I understood your concern correctly, would you like to display somewhat a preview before submit so that users will be able to review their submission like the date they selected?

You can add this by adding the Preview Before submit widget. Here's the link to it: https://widgets.jotform.com/widget/preview_before_submit 

Here's how you can add a widget on your form: https://www.jotform.com/help/252-How-to-Add-a-Widget-to-your-Form 

Let us know if this works for you. If not, please do provide us more information on what you would like to output as a result.

I'll try to explain better. I'm using the Date Reservation widget. I have it set so you can pick multiple days. I want to the user to see something that says (first date-last date). 

You might consider adding the Preview Before Submit widget to your form. The form users will see their selected dates in this case.

Example:

If you need any further assistance, please let us know.