In English, the femenine of blond is blonde, since the word was borrowed from French.
In english irrespective of the gender, the word blonde refers to both masculine and feminine . In french however, blond masculine and blondE feminine. I am open to correction.
Do you pronounce the 't' in "C'est" because the next word starts with a vowel? I can't tell if this is the way to do it, or if the duolingo synthesized voice is messing this up (it does pretty well, most of the time!).
The audio is rather good, just a bit messed up on the 'l' in "blonde", but otherwise it's good enough. Yes, in this case the "t" is pronounced (because of the vowel in "une"). It's called a "liaison".
I put There is a blond girl and it counted it wrong. In the lesson notes, it says c'est can be 'there is'. Am I right?
I think in that case you would say "Il y a une fille blonde" rather than "c'est une..."
Why is "it is a blond girl" wrong? They tell me it has to be "it is one blond girl"
Ce (third-person pronoun) is non-specific to gender and number.
There is no direct equivalent in English. So we have to choose between he, she, it, that, they, these, those.
Select the one that best describes the subject and the situation.
In this case, you're talking about a girl, so the best choice is "she", in my opinion.
Of course, your opinion might be different. If they're emphasizing a specific blonde girl, you might translate it as "That (or this) is a blonde girl.