Testimonial block contain repeater item that allow you to add as much as possible slides item as testimonial items.
In this setting, you will see the repeater items and button to add more item. Inside each item you can find a form to fill the testimonial content.
This section you will be able to set their style like colors, font size, font weight or even decide to not shown the elements.
This setting tabs contain slider option. You can set how item show in one slide. Also set other options such as navigation arrow, slides loop and play time.