"The crab eats the strawberry."
Translation:Krabban äter jordgubben.
It can mean both. I guess you can translate it the way you think suits the context/style etc. best. German has stgh similar, btw :) although you can form "ist essend" to mimick "is eating" it'd sound artificial, instead, we always say "er/sie/es isst". But there's ways to signal the ongoing process e.g. by saying: "Er isst gerade" - "He is eating right now."
The point of these very strange sentences is to make sure you understand the meaning of the words and the grammar, and aren't only relying on context clues to translate sentences. You are not meant to use Duolingo to memorize sentences word-by-word and repeat them, you are meant to actually understand the language and how it's structured.