You can customize the “Star Rate Prefix” using the Combo Blocks plugin. This article will help you to customize the prefix of Star Rate Block.
To begin, insert a “Star Rate” block.

Click on the “Postfix” tab.

Here, you can add Postfix text.

Now click on the “Styles” tab.

Here you can customize the style of the postfix. If you don’t know how to style an element, then read this document.

You can customize the Postfix of the Star Rate Block using this method.