The spanish "b/v"
I have only been using Duolingo up until recently to learn Spanish. It wasn't until a friend who learned Spanish in school brought it to my attention that I realized all b's and v's in Spanish are a slightly different "b" from English. Without knowing that, I've just been pronouncing them as b's and v's as they seem to be pronounced in the exercises. Not sure how this could be resolved, but it would be good to have a little pronunciation guide I guess.
Something to consider is the huge number of people that speak Spanish. Unfortunately, I don't think a comprehensive pronunciation guide would be comprehensive enough to be useful, considering all the accents that are present in the language itself.
My understanding is that pronunciation in Spanish is fairly straightforward once you know the rules. As far as I can tell all that I've been missing is the knowledge that "b/v" is different than in English.