"The girl and the boy are reading a newspaper."
Translation:Pigen og drengen læser en avis.
Yes. (Although technically speaking, it's not 'masculine' or 'feminine' genders in Danish, but it's the same idea; the nouns belong to one or the other 'class' of nouns and that affects the way they behave grammatically, for example, which article they take. So some nouns take the 'en' article and others take 'et'.)
Hi there 'en' and 'et' both are for 'a' unfortunately there are no rules for 'en' and 'et' words. Just about 75% of words fall in the 'en' category and the rest 25% in the 'et'. The way to know is to look in the dictionary if the word is an 'et' or an 'en' word. I hope this helps.