So, if you have a look at the tips related to this section (months/seasons/time), it becomes a bit clearer why this apparently random word shows up.
"Meán Fómhair and Deireadh Fómhair literally mean middle of the harvest and end of the harvest." This explains why the word "meán" shows up in this section.
The average score, the average mark, is what I would take it to mean.
Duolingo uses 'he's' as a short form of 'he has' sometimes. This is not something I've ever come across in English before. It wouldn't be 'he is' as aige never means that - I think that would be "Tá sé an meán"
If you use the "has got" construction, then "he's got" is common enough ("he's got the average", for example), but you're right, Duolingo has a problem with contracting "he has" to "he's" when there is no "got", and it's not just a problem with the Irish course - it crops up on other courses too.
Yes, I didn't think of it's use as an auxiliary verb (if that's the correct term). I've literally never come across it as a contraction of 'he has' as a possessive though.
I'm pretty sure that I sometimes say "he's a ..." - "he's a head on him like a jockey's ....", "he's a new job, and there's a lot of travel", "he's a new boat, so he's probably gone fishing". Even though I might say "he's" in these cases, I'd usually write "he has".
Of course, I'm not even sure whether "he's probably gone fishing" should be "he is probably gone fishing" or "he has probably gone fishing", but "he's asked me to help him" is definitely "he has".
The last example is using has as an auxiliary verb though. The earlier ones, using has as a possessive, sound totally weird to my English ears. I would always say "He's got a new boat/job or whatever". It's obviously a difference in idiom. Some commentators have objected that using 'got' in that way is ungrammatical and sounds weird.
"Listen - I've an idea" is fine to my ears. I think if the people building this course use contractions of the possessive meaning of "have" in this way, it's fair to assume that for them at least it's perfectly good English. People doing this course are spread right across the globe and their English-speaking ears are different. Some aren't native speakers, others are but in very different regions. I'm just happy if I can trust that the Irish is right.
I've an idea (I have an idea) is stating possession, but it isn't a possessive in the grammatical sense.
Grammatically it's exactly equivalent to what you called a contraction of 'he has' as a possessive. I agree that the word 'possessive' in grammar usually refers to possessive pronouns etc rather than to verbs which basically just mean 'possess', but I'd argue that the grammar behind the contractions in 'He's a boat in the harbour' and 'I've an idea' is the same.
Yes, of course. This discussion has been going on so long I forgot what it was originally about. It just sounds wrong to me. I'd never contract 'he has' to make 'he's' because that is a contraction of 'he is'. If you imagine a sentence like 'he's an apple' and think how weird that sounds to somebody who thinks that way
I can't tell from the app how old these comments are so sorry if I've awoken something long dormant.
I agree that "He's an apple" ought only to mean one thing, but "He's an apple in his pocket" seems fine to me, especially perhaps in an Irish accent.
This issues doesn't really have anything to do with the Irish course - it's a "feature" of the Duolingo engine that it contracts "he has" to "he's" even in circumstances where most English speakers would be careful to distinguish between "he has" and "he is", precisely because of the confusion that has been demonstrated in this particular discussion.
From comments that I've read in other forums, the problem has caused problems on other courses too.