"She eats strawberries."
Translation:Elle mange des fraises.
There are basic rules that you would need to be aware of:
Look at the singular: she eats a strawberry = elle mange une fraise.
Back to plural: she eats strawberries (in English "a" does not have a plural form) = elle mange des fraises, because "des" is the plural form of "une" and "un" as well:
- she eats sweets = elle mange des bonbons