I think the problem for us English speakers is the Italian prepositions don't slice along the same lines as English. In some phrases where we use "in", Italian uses "in", but for others it uses "a" or "per". I'm not sure there's an easy rule for it.
Though I notice these time words all tend to use "a" instead of "in". Maybe that's a rule? Siamo a aprile -> We are in April Bevo caffè alla mattina -> I drink coffee in the morning
I believe nella is more of being inside something physically. Something like months and seasons we are in them but not technically. Its more of a rule in the grammar to use a or di when referring to months seasons or time (morning, night, etc). And as far as "alla mattina" might be a regional thing in Italy. Its much more safer just to say "Bevo caffe di mattina". Still means the same thing and personally sounds more natural. (My family is from Palermo, Sicily so maybe in northern parts of Italy they say "alla mattina" but I never heard my family say it).
I think that is actually the more accurate translation, or at least an alternative one (but I'm not entirely sure). If you remember back in the earlier parts, we could use a noun to describe another noun by putting "al" in it, such as "Voglio del gelato al cioccolato" being "I want some chocolate ice cream." Perhaps that's what's going on here, but because "mattina" is feminine, we use the feminine form which would be "alla." So the sentence "Bevo caffè alla mattina," could very well be "I drink morning coffee."
Again, I'm not sure so it would be appreciated if someone more experienced could verify this.
"At the morning" (or even "to the morning") is what it literally means, but that isn't a "translation." We silly English speakers don't tend to put it that way. I might frown at the morning, but I never drink [whatever] at the morning. Duo tries to put "the phrase as it's used" against the equivalent "phrase used the same way" when doing translations. It's not the only way to translate, as is frequently pointed out on these forums.
Then there's always fun things like "at the break of dawn," or "come morning," or... Isn't language fun?
Duo is not 100% consistent about translations. But - to be fair - neither are linguists. You can't always be. (Try translating some rich ancient Greek poetry into modern what-ever sometime, you'll get what I mean.) Language is Human, which means less than completely predictable. :)
Re the previous question please can you apply British English when as i am you have a British user with a British phone/mobile location. E.g. I might not know that 'fall' is the third season of the year. We call it Autumn. US English is different from British English. E.g. Pants are underwear not trousers which cover your legs. Thanks
When you have questions about the real meaning of a word you can go to other online sources for help. Such as collins online dictionary, https://www.collinsdictionary.com/dictionary/italian-english/mattina where you will see that "mattina" means morning, and only morning. Not sure where you saw it being used as "evening"
But again you can consult collins, https://www.collinsdictionary.com/dictionary/english-italian/evening and find that evening is "sera."
Just some thoughts. Hope it helps.
Why can't we omit "the" article in English? Like "I drink coffee in _ morning"? My thought was that it should be fine with present simple, as it is not about some particular morning, but about mornings in general. So, was it incorrect translation from Italian, or just incorrect English?
It's common in the romance languages to say things like "of the" or "to the" or such where English would say "in the"... If you think about it, "to the" or "at the" morning makes more sense than "in the." What's inside a morning? It sounds right to us only because we're used to it. Spanish does the same thing. "en la" means in the, on the, and a bunch of other things. Go figure...