The single most common advice language teachers give is
Mistakes are okay.
Never have I heard math, chemistry, biology, or physics teachers ever say: mistakes are okay, don’t be afraid to make mistakes...
But language teachers and especially native language teachers say that all the time – as I said it’s the most common piece of advice native English teachers give to language learners.
it’s such a useless and meaningless advice. It's like telling a boxer "Don't be afraid of getting punched" ... it's not a very helpful advice, is it?
Of course the boxer will get punched, he knows it, but telling him to not be afraid won't make him a better athlete. Teach him how NOT to get punched or get punched less.
Well I'm not a boxing coach, but I am a language teacher and as such I teach my students how not to make mistakes.