Conjugation. In English most verbs only get a -s in the third person (I walk, he walks), but German has a lot more of that.
trinken — to drink
ich trinke — I drink
du trinkst — you drink
er trinkt — he drinks
wir trinken — we drink
ihr trinkt — you (plural) drink
sie trinken — they drink
a minor typo of "wien" and "wein"
Wien and Wein are both capitalised, and they are completely different words in German -- Wien is a city (the capital of Austria) and Wein is a drink made from grapes.
They're as different as "cone" and "cane" in English.
If your typo results in something that is a real word, it will get marked wrong, the same as if you had deliberately used the wrong word -- because Duo can't tell the difference.