Translation:Learners of French are incredible.
Apprenant is correct and accepted by the Larousse dictionary even if it is not recognized yet by the Académie Française.
"Learners" is not common usage in American English. We tend to call ourselves "students" even when self-taught.
'Learners' is a word that has crept into UK English in recent years as a replacement for 'pupils' (school kids); just as university students have become 'clients' or 'customers'! And by now I guess you've guessed that I don't like it ;)
Unfortunately, using learners in this way in the translation sounds a little contrived, but its natural alternative - 'The French students..... ' is ambiguous as without further context, this could refer to their nationality or their subject.
Not at all!
incroyable → incredible
pas crédible/pas plausible → not credible
You can write it either way depending if you prefer to have the article "le" in front of French.
du (de le) français or de français, both are acceptable.
Wow. Is the article always optional with languages? Je parle anglais/l'anglais?
Only with the verb "parler" can you say "je parle anglais, je parle l'anglais, je parle en anglais".
With other verbs you will use "le" or "en":
- Je connais l'anglais
- J'écris en anglais.
It is a recent word and it is more and more in use. And it is in serious dictionaries.
incredible means unbelievable but Duo does not accept this - reported.
Some do, and it is a word in the Larousse, even though it is not recognized by the Académie Française.