Testimonials are similar to product reviews, except they are about your whole store and not specific to a single product.
Testimonials are essentially store reviews.
In order to show your testimonials, you need to add a testimonial widget to your site.
How to add a testimonial widget
Find the Widget section on the left-hand side of your dashboard
Click the + Add Widget button
Select Show Something Else
Type in 'Testimonials' in the search bar
Click the Increase Trust drop-down menu
Select Testimonial Carousel
Now, you need to decide where you want to show your testimonials. You can show them on your:
Once you decide where you want to show your testimonial
Make sure that you are on the Location tab
Under Store Section click Change
Choose where you want to display your widget
When you are ready to show your testimonial, click the green Launch button