There are 2 ways that spring to mind:
The first is that verbs are conjugated differently for different articles. In this case the base verb "essen" becomes "isst" to fit with "sie" (she). If it had been "Sie" (you), then the verb would've been conjugated to "essen". So by looking at the verb you can tell which "S/sie" is being used.
The second, and less obvious, way is that "Sie" is not just "you" but "you" (formal). The context of the sentence/situation etc. will often help differentiate this but usually in basic German language teaching, "Sie" is used all that often anyway.
Hope that helps :)
Actually there are 3 sie`s. sie they, Sie you formal, and sie she. pay attention to the case I typed them in. You can tell sie they and sie she apart by the word that follows them. For example, sie haben they have and sie hat she has. sie they and Sie you formal have identical words that follow them. For example Sie essen you eat and sie essen they eat.If there is sie they at the front of the sentence I do not know what to do but for the rest they stay their case no matter what.
It's really frustrating that Duolingo doesn't give any feedback about which sounds it thinks you are getting wrong. It is one of the few places where I find Rosetta Stone doing a better job. There you could at least compare audiographs.
With both, there are sentences that have been marked correct when I know my pronounciation has been widly off, but (like here) I have no Idea what is triggering a failure response.
no, it sounds exactly the same. "Being a strawberry" being a rare situation, the context usually solves it. Furthermore: She eats an apple - Sie isst einen (Akkusativ) Apfel. She is an apple - Sie ist ein (Nominativ) Apfel. With feminine nouns, both forms are identical. Yes, it's tricky, but watch the context and you'll know what it's all about. We native speakers have do the same.