The plugin has been built so you can translate everything into your own language.
To do this you will need to sign into your WordPress account. If you don’t have an account, you can register here
After logging in go to the plugin translation page: https://wordpress.org/plugins/quick-interest-slider/#developers
Click on the ‘Translate’ link and follow the instructions.
The alternative is to install a translation plugin. I like Loco Translate.
If you need help with setting things up send me a message