Welcome! 
There is a theme component installed automatically with this theme.
It’s called Search Banner.
Usually theme components has settings or translations that you can change. To do so:
- Go to
Admin - Click on
Themes
- Click on
Componentsand look for Discourse Search Banner component:
- If you scroll down in the right panel, you will the translations. You can change them here:
If you are new to theme, I recommend reading the Beginner’s guide to using Discourse Themes!