"It is a big loss for the Argentinian people."
Translation:É uma grande perda para o povo argentino.
If you, like me, think ‘grande perda’ looks the wrong way around, well I've done some searching and it seems that a) ‘grande’ before the noun means ‘great’ (rather than ‘big’) and b) ‘grande perda’ (‘great loss’) is a set phrase and ‘perda grande’ (‘big loss’) does occur but only very rarely, to the point that I accept that Duolingo rejects it.
Yes. A gente = we (including the speaker) / gente = people. So, in a context where there is a gente = people (not we) you use "o povo" / "a população". A empresa está procurando gente para trabalhar - too informal (the company is looking for people to work there). A gente vai à praia? = are we going to the beach?